expression: fix wrong caseWhen function for enum type (#29454) (#29510)

close #29357
pingcap · Jan 27, 2022 · 2780dfb · 2780dfb
1 parent f9157d8
commit 2780dfb
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Showing 3 changed files with 22 additions and 1 deletion.
diff --git a/expression/builtin_control.go b/expression/builtin_control.go
@@ -227,6 +227,14 @@ func (c *caseWhenFunctionClass) getFunction(ctx sessionctx.Context, args []Expre
 		return nil, err
 	}
 	bf.tp = fieldTp
+	if fieldTp.Tp == mysql.TypeEnum || fieldTp.Tp == mysql.TypeSet {
+		switch tp {
+		case types.ETInt:
+			fieldTp.Tp = mysql.TypeLonglong
+		case types.ETString:
+			fieldTp.Tp = mysql.TypeVarchar
+		}
+	}
 
 	switch tp {
 	case types.ETInt:

diff --git a/expression/constant_fold.go b/expression/constant_fold.go
@@ -140,7 +140,7 @@ func caseWhenHandler(expr *ScalarFunction) (Expression, bool) {
 			foldedExpr.GetType().Decimal = expr.GetType().Decimal
 			return foldedExpr, isDeferredConst
 		}
-		return BuildCastFunction(expr.GetCtx(), foldedExpr, foldedExpr.GetType()), isDeferredConst
+		return foldedExpr, isDeferredConst
 	}
 	return expr, isDeferredConst
 }

diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -9737,6 +9737,19 @@ func (s *testIntegrationSuite) TestControlFunctionWithEnumOrSet(c *C) {
 	tk.MustExec("insert into t values(1,1,1),(2,1,1),(1,1,1),(2,1,1);")
 	tk.MustQuery("select if(A, null,b)=1 from t;").Check(testkit.Rows("<nil>", "<nil>", "<nil>", "<nil>"))
 	tk.MustQuery("select if(A, null,b)='a' from t;").Check(testkit.Rows("<nil>", "<nil>", "<nil>", "<nil>"))
+
+	// issue 29357
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(`a` enum('y','b','Abc','null','1','2','0')) CHARSET=binary;")
+	tk.MustExec("insert into t values(\"1\");")
+	tk.MustQuery("SELECT count(*) from t where (null like 'a') = (case when cast('2015' as real) <=> round(\"1200\",\"1\") then a end);\n").Check(testkit.Rows("0"))
+	tk.MustQuery("SELECT (null like 'a') = (case when cast('2015' as real) <=> round(\"1200\",\"1\") then a end) from t;\n").Check(testkit.Rows("<nil>"))
+	tk.MustQuery("SELECT 5 = (case when 0 <=> 0 then a end) from t;").Check(testkit.Rows("1"))
+	tk.MustQuery("SELECT '1' = (case when 0 <=> 0 then a end) from t;").Check(testkit.Rows("1"))
+	tk.MustQuery("SELECT 5 = (case when 0 <=> 1 then a end) from t;").Check(testkit.Rows("<nil>"))
+	tk.MustQuery("SELECT '1' = (case when 0 <=> 1 then a end) from t;").Check(testkit.Rows("<nil>"))
+	tk.MustQuery("SELECT 5 = (case when 0 <=> 1 then a else a end) from t;").Check(testkit.Rows("1"))
+	tk.MustQuery("SELECT '1' = (case when 0 <=> 1 then a else a end) from t;").Check(testkit.Rows("1"))
 }
 
 func (s *testIntegrationSuite) TestComplexShowVariables(c *C) {