plan: refine the handle check to use point get plan for prepare state…

…ment (pingcap#7732)

cmd/explaintest/r/select.result

@@ -320,3 +320,11 @@ HashLeftJoin_10	156250000.00	root	left outer join, inner:HashLeftJoin_16, left c
   │ └─TableScan_17	10000.00	cop	table:t3, range:[-inf,+inf], keep order:false, stats:pseudo
   └─TableReader_20	10000.00	root	data:TableScan_19
     └─TableScan_19	10000.00	cop	table:t4, range:[-inf,+inf], keep order:false, stats:pseudo
+drop table if exists t;
+create table t(a bigint primary key, b bigint);
+desc select * from t where a = 1;
+id	count	task	operator info
+Point_Get_1	1.00	root	table:t, handle:1
+desc select * from t where a = '1';
+id	count	task	operator info
+Point_Get_1	1.00	root	table:t, handle:1

cmd/explaintest/t/select.test

@@ -29,7 +29,7 @@ SELECT 1, @a, @@autocommit as a, c1 from t;
 SET @b = "123";
 SELECT @b + "123";
 # TODO: the field name for 1 + 1 should be "1 + 1", but now is 2
-# we may discuss whether to support it like in MySQL later. 
+# we may discuss whether to support it like in MySQL later.
 SELECT 1 + 1;
 
 SELECT 1 a, 1 as a, 1 + 1 a;
@@ -60,7 +60,7 @@ SELECT * from (SELECT 1, 1) as a;
 --error ER_DUP_FIELDNAME
 SELECT * from (SELECT * FROM t, t2) as a;
 
-# Select bool field 
+# Select bool field
 DROP TABLE IF EXISTS t;
 CREATE TABLE t (c1 INT, c2 INT);
 INSERT INTO t VALUES (1, 2), (1, 1), (1, 3);
@@ -86,7 +86,7 @@ select c2 from t where not null is null;
 # unary field name
 select !(1 + 2);
 
-# - + 
+# - +
 select + - 1, --1, +-+-+1, + "123";
 select --------------------1, ++++++++++++++++++++1;
 select --+(1 + 1), +-+-(1 * 1);
@@ -158,3 +158,8 @@ select count(a) from t where b>0 group by a, b order by a limit 1;
 drop table if exists t;
 create table t (id int primary key, a int, b int);
 explain select * from (t t1 left join t t2 on t1.a = t2.a) left join (t t3 left join t t4 on t3.a = t4.a) on t2.b = 1;
+
+drop table if exists t;
+create table t(a bigint primary key, b bigint);
+desc select * from t where a = 1;
+desc select * from t where a = '1';

planner/core/point_get_plan.go

@@ -184,7 +184,7 @@ func tryPointGetPlan(ctx sessionctx.Context, selStmt *ast.SelectStmt) *PointGetP
 		return nil
 	}
 	handleDatum := findPKHandle(tbl, pairs)
-	if handleDatum.Kind() == types.KindInt64 {
+	if handleDatum.Kind() != types.KindNull {
 		if len(pairs) != 1 {
 			return nil
 		}
@@ -193,15 +193,19 @@ func tryPointGetPlan(ctx sessionctx.Context, selStmt *ast.SelectStmt) *PointGetP
 			return nil
 		}
 		p := newPointGetPlan(ctx, schema, tbl)
-		p.Handle = handleDatum.GetInt64()
+		var err error
+		p.Handle, err = handleDatum.ToInt64(ctx.GetSessionVars().StmtCtx)
+		if err != nil {
+			return nil
+		}
 		return p
 	}
 	for _, idxInfo := range tbl.Indices {
 		if !idxInfo.Unique {
 			continue
 		}
 		if idxInfo.State != model.StatePublic {
-			return nil
+			continue
 		}
 		idxValues := getIndexValues(idxInfo, pairs)
 		if idxValues == nil {