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GP-121 copy exercise from completed
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‎2-0-jdbc-api/2-0-2-create-table/README.MD

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# <img src="https://raw.githubusercontent.com/bobocode-projects/resources/master/image/logo_transparent_background.png" height=50/>Account db initializer exercise :muscle:
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Improve your database design and SQL skills
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### Task
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`AccountDbInitializer` provides an API that allows to create(initialize) a database (one table). It contains a *javadoc*
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that specifies database requirements. `AccountDbInitializer` has a field `DataSource`. Your job is to use that
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`dataSource` and **implement the todo section**. E.g. implement the method `init()` that should **create an account db.**
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The purpose of the task is to **design a database table following docs and naming convention and implement it using SQL and
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JDBC API.**
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To verify your implementation, run `AccountDbInitializerTest.java`
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### Pre-conditions :heavy_exclamation_mark:
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You're supposed to be familiar with database design and naming convention, *JDBC API* and *SQL*
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### How to start :question:
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* Just clone the repository and start implementing the **todo** section, verify your changes by running tests
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* If you don't have enough knowledge about this domain, check out the [links below](#related-materials-information_source)
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* Don't worry if you got stuck, checkout the **exercise/completed** branch and see the final implementation
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### Related materials :information_source:
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* [JDBC API basics tutorial](https://github.com/bobocode-projects/jdbc-api-tutorial/tree/master/jdbc-basics) <img src="https://raw.githubusercontent.com/bobocode-projects/resources/master/image/logo_transparent_background.png" height=20/>
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‎2-0-jdbc-api/2-0-2-create-table/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<parent>
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<artifactId>2-0-jdbc-api</artifactId>
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<groupId>com.bobocode</groupId>
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<version>1.0-SNAPSHOT</version>
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</parent>
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<modelVersion>4.0.0</modelVersion>
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<artifactId>2-0-2-create-table</artifactId>
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<dependencies>
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<dependency>
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<groupId>com.bobocode</groupId>
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<artifactId>jdbc-util</artifactId>
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<version>1.0-SNAPSHOT</version>
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</dependency>
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</dependencies>
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</project>

‎2-0-jdbc-api/2-0-2-create-table/src/main/java/com/bobocode/AccountDbInitializer.java

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package com.bobocode;
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import javax.sql.DataSource;
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import java.sql.Connection;
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import java.sql.SQLException;
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import java.sql.Statement;
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/**
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* {@link AccountDbInitializer} provides an API that allow to initialize (create) an Account table in the database
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*/
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public class AccountDbInitializer {
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private DataSource dataSource;
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public AccountDbInitializer(DataSource dataSource) {
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this.dataSource = dataSource;
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}
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/**
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* Creates an {@code account} table. That table has a identifier column {@code id} with type {@code bigint}.
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* It also contains an {@code email} column that is mandatory and should have unique value. This column is be able
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* to store any valid email. The table also has columns {@code first_name}, {@code last_name}, and {@code gender}
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* that are typical string columns with 255 characters, and are mandatory. Account {@code birthday} is stored
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* in the {@code DATE} mandatory column. The value of account balance is not mandatory, and is stored
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* in the {@code balance} column that is a {@code DECIMAL} number with {@code precision = 19} ,
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* and {@code scale = 4}. A column {@code creation_time} stores a {@code TIMESTAMP}, is mandatory, and has a default
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* value that is set to the current timestamp using database function {@code now()}. Table primary key
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* is an {@code id}, and corresponding constraint is named {@code "account_pk"}. An unique constraint that
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* is created for {@code email column} is called "account_email_uq"
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*
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* @throws SQLException
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*/
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public void init() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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statement.execute("CREATE TABLE account(" +
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"id BIGINT," +
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"email VARCHAR(255) NOT NULL," +
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"first_name VARCHAR(255) NOT NULL," +
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"last_name VARCHAR(255) NOT NULL," +
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"gender VARCHAR(255) NOT NULL," +
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"birthday DATE NOT NULL," +
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"balance DECIMAL(19,4)," +
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"creation_time TIMESTAMP NOT NULL DEFAULT now()," +
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"CONSTRAINT account_pk PRIMARY KEY (id)," +
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"CONSTRAINT account_email_uq UNIQUE (email)" +
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");");
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}
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}
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}

‎2-0-jdbc-api/2-0-2-create-table/src/test/java/com/bobocode/AccountDbInitializerTest.java

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package com.bobocode;
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import com.bobocode.util.JdbcUtil;
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import org.junit.jupiter.api.BeforeAll;
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import org.junit.jupiter.api.Test;
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import javax.sql.DataSource;
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import java.sql.Connection;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.sql.Statement;
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import java.util.ArrayList;
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import java.util.List;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import static org.junit.jupiter.api.Assertions.assertTrue;
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public class AccountDbInitializerTest {
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private static DataSource dataSource;
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@BeforeAll
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static void init() throws SQLException {
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dataSource = JdbcUtil.createDefaultInMemoryH2DataSource();
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AccountDbInitializer dbInitializer = new AccountDbInitializer(dataSource);
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dbInitializer.init();
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}
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@Test
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void testTableHasCorrectName() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SHOW TABLES");
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resultSet.next();
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String tableName = resultSet.getString("table_name");
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assertEquals("account", tableName);
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}
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}
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@Test
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void testTableHasPrimaryKey() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.CONSTRAINTS" +
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" WHERE table_name = 'account' AND constraint_type = 'PRIMARY_KEY';");
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boolean resultIsNotEmpty = resultSet.next();
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assertTrue(resultIsNotEmpty);
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}
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}
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@Test
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void testPrimaryKeyHasCorrectName() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.CONSTRAINTS" +
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" WHERE table_name = 'account' AND constraint_type = 'PRIMARY_KEY';");
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resultSet.next();
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String pkConstraintName = resultSet.getString("constraint_name");
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assertEquals("account_pk", pkConstraintName);
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}
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}
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@Test
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void testPrimaryKeyBasedOnIdField() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.CONSTRAINTS" +
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" WHERE table_name = 'account' AND constraint_type = 'PRIMARY_KEY';");
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resultSet.next();
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String pkColumn = resultSet.getString("column_list");
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assertEquals("id", pkColumn);
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}
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}
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@Test
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void testTableHasCorrectAlternativeKey() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.CONSTRAINTS" +
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" WHERE table_name = 'account' AND constraint_type = 'UNIQUE';");
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resultSet.next();
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String uniqueConstraintName = resultSet.getString("constraint_name");
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String uniqueConstraintColumn = resultSet.getString("column_list");
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assertEquals("account_email_uq", uniqueConstraintName);
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assertEquals("email", uniqueConstraintColumn);
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}
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}
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@Test
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void testTableHasAllRequiredColumns() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account';");
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List<String> columns = fetchColumnsNames(resultSet);
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assertEquals(8, columns.size());
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assertTrue(columns.containsAll(List.of("id", "first_name", "last_name", "email", "gender", "balance", "birthday", "creation_time")));
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}
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}
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private List<String> fetchColumnsNames(ResultSet resultSet) throws SQLException {
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List<String> columns = new ArrayList<>();
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while (resultSet.next()) {
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String columnName = resultSet.getString("column_name");
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columns.add(columnName);
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}
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return columns;
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}
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@Test
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void testRequiredColumnsHaveHaveNotNullConstraint() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND nullable = false;");
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List<String> notNullColumns = fetchColumnsNames(resultSet);
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assertEquals(7, notNullColumns.size());
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assertTrue(notNullColumns.containsAll(List.of("id", "first_name", "last_name", "email", "gender", "birthday", "creation_time")));
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}
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}
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@Test
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void testIdHasTypeBiInteger() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'id';");
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resultSet.next();
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String idTypeName = resultSet.getString("type_name");
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assertEquals("BIGINT", idTypeName);
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}
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}
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@Test
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void testCreationTimeHasTypeTimestamp() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'creation_time';");
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resultSet.next();
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String creationTimeColumnType = resultSet.getString("type_name");
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assertEquals("TIMESTAMP", creationTimeColumnType);
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}
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}
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@Test
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void testCreationTimeHasDefaultValue() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'creation_time';");
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resultSet.next();
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String creationTimeColumnDefault = resultSet.getString("column_default");
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assertEquals("NOW()", creationTimeColumnDefault);
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}
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}
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@Test
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void testEmailColumnHasCorrectSize() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'email';");
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resultSet.next();
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String emailColumnType = resultSet.getString("type_name");
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int emailColumnMaxLength = resultSet.getInt("character_maximum_length");
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assertEquals("VARCHAR", emailColumnType);
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assertEquals(255, emailColumnMaxLength);
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}
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}
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@Test
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void testBirthdayColumnHasCorrectType() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'birthday';");
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resultSet.next();
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String birthdayColumnType = resultSet.getString("type_name");
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assertEquals("DATE", birthdayColumnType);
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}
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}
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@Test
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void testBalanceColumnHasCorrectType() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'balance';");
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resultSet.next();
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String balanceColumnType = resultSet.getString("type_name");
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int balanceColumnPrecision = resultSet.getInt("numeric_precision");
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int balanceColumnScale = resultSet.getInt("numeric_scale");
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assertEquals("DECIMAL", balanceColumnType);
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assertEquals(19, balanceColumnPrecision);
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assertEquals(4, balanceColumnScale);
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}
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}
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@Test
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void testBalanceIsNotMandatory() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT * FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND column_name = 'balance';");
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resultSet.next();
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boolean balanceColumnIsNullable = resultSet.getBoolean("nullable");
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assertTrue(balanceColumnIsNullable);
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}
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}
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@Test
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void testStringColumnsHaveCorrectTypeAndLength() throws SQLException {
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try (Connection connection = dataSource.getConnection()) {
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Statement statement = connection.createStatement();
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ResultSet resultSet = statement.executeQuery("SELECT column_name FROM INFORMATION_SCHEMA.COLUMNS" +
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" WHERE table_name = 'account' AND type_name = 'VARCHAR' AND character_maximum_length = 255;");
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List<String> stringColumns = fetchColumnsNames(resultSet);
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assertEquals(4, stringColumns.size());
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assertTrue(stringColumns.containsAll(List.of("first_name", "last_name", "email", "gender")));
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}
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}
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}

‎2-0-jdbc-api/pom.xml

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<packaging>pom</packaging>
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<modules>
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<module>2-0-2-create-table</module>
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<module>2-1-1-product-dao</module>
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</modules>
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