*: Convert CaseExpr to ScalarFunction and clean up (pingcap#1377)

* *: support CaseExpr to ScalarFunction and tiny clean up
jiankg · Jul 4, 2016 · 5520e26 · 5520e26
1 parent c72917d
commit 5520e26
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Showing 4 changed files with 201 additions and 90 deletions.
diff --git a/evaluator/builtin.go b/evaluator/builtin.go
@@ -150,6 +150,7 @@ var Funcs = map[string]Func{
 	ast.IsTruth:    {isTrueOpFactory(opcode.IsTruth), 1, 1},
 	ast.IsFalsity:  {isTrueOpFactory(opcode.IsFalsity), 1, 1},
 	ast.Like:       {builtinLike, 1, 3},
+	ast.Case:       {builtinCaseWhen, 1, -1},
 	ast.RowFunc:    {builtinRow, 2, -1},
 }
 

diff --git a/evaluator/builtin_other.go b/evaluator/builtin_other.go
@@ -83,6 +83,30 @@ func builtinOrOr(args []types.Datum, _ context.Context) (d types.Datum, err erro
 	return
 }
 
+func builtinCaseWhen(args []types.Datum, _ context.Context) (d types.Datum, err error) {
+	l := len(args)
+	for i := 0; i < l-1; i += 2 {
+		if args[i].IsNull() {
+			continue
+		}
+		b, err1 := args[i].ToBool()
+		if err1 != nil {
+			return d, errors.Trace(err1)
+		}
+		if b == 1 {
+			d = args[i+1]
+			return
+		}
+	}
+	// when clause(condition, result) -> args[i], args[i+1]; (i >= 0 && i+1 < l-1)
+	// else clause -> args[l-1]
+	// If case clause has else clause, l%2 == 1.
+	if l%2 == 1 {
+		d = args[l-1]
+	}
+	return
+}
+
 func builtinLike(args []types.Datum, _ context.Context) (d types.Datum, err error) {
 	if args[0].IsNull() {
 		return

diff --git a/executor/executor_test.go b/executor/executor_test.go
@@ -1345,6 +1345,8 @@ func (s *testSuite) TestBuiltin(c *C) {
 	defer testleak.AfterTest(c)()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
+
+	// for is true
 	tk.MustExec("drop table if exists t")
 	tk.MustExec("create table t (a int, b int, index idx_b (b))")
 	tk.MustExec("insert t values (1, 1)")
@@ -1356,19 +1358,12 @@ func (s *testSuite) TestBuiltin(c *C) {
 	result.Check(nil)
 	result = tk.MustQuery("select * from t where a is not true")
 	result.Check(nil)
+	// for in
 	result = tk.MustQuery("select * from t where b in (a)")
 	result.Check(testkit.Rows("1 1", "2 2"))
 	result = tk.MustQuery("select * from t where b not in (a)")
 	result.Check(testkit.Rows("3 2"))
 
-	tk.MustExec("drop table if exists t")
-	tk.MustExec("create table t (a varchar(255), b int)")
-	tk.MustExec("insert t values ('abc123', 1)")
-	tk.MustExec("insert t values ('ab123', 2)")
-	result = tk.MustQuery("select * from t where a like 'ab_123'")
-	rowStr := fmt.Sprintf("%v %v", []byte("abc123"), "1")
-	result.Check(testkit.Rows(rowStr))
-
 	// test cast
 	result = tk.MustQuery("select cast(1 as decimal(1,2))")
 	result.Check(testkit.Rows("1.00"))
@@ -1378,6 +1373,48 @@ func (s *testSuite) TestBuiltin(c *C) {
 	result.Check(testkit.Rows("1991-09-05 11:11:11"))
 	result = tk.MustQuery("select cast('11:11:11' as time)")
 	result.Check(testkit.Rows("11:11:11"))
+
+	// for like
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a varchar(255), b int)")
+	tk.MustExec("insert t values ('abc123', 1)")
+	tk.MustExec("insert t values ('ab123', 2)")
+	result = tk.MustQuery("select * from t where a like 'ab_123'")
+	rowStr := fmt.Sprintf("%v %v", []byte("abc123"), "1")
+	result.Check(testkit.Rows(rowStr))
+
+	// case
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a varchar(255), b int)")
+	tk.MustExec("insert t values ('str1', 1)")
+	result = tk.MustQuery("select * from t where a = case b when 1 then 'str1' when 2 then 'str2' end")
+	rowStr1 := fmt.Sprintf("%v %v", []byte("str1"), "1")
+	result.Check(testkit.Rows(rowStr1))
+	result = tk.MustQuery("select * from t where a = case b when 1 then 'str2' when 2 then 'str3' end")
+	result.Check(nil)
+	tk.MustExec("insert t values ('str2', 2)")
+	result = tk.MustQuery("select * from t where a = case b when 2 then 'str2' when 3 then 'str3' end")
+	rowStr2 := fmt.Sprintf("%v %v", []byte("str2"), "2")
+	result.Check(testkit.Rows(rowStr2))
+	tk.MustExec("insert t values ('str3', 3)")
+	result = tk.MustQuery("select * from t where a = case b when 4 then 'str4' when 5 then 'str5' else 'str3' end")
+	rowStr3 := fmt.Sprintf("%v %v", []byte("str3"), "3")
+	result.Check(testkit.Rows(rowStr3))
+	result = tk.MustQuery("select * from t where a = case b when 4 then 'str4' when 5 then 'str5' else 'str6' end")
+	result.Check(nil)
+	result = tk.MustQuery("select * from t where a = case  when b then 'str3' when 1 then 'str1' else 'str2' end")
+	result.Check(testkit.Rows(rowStr3))
+	tk.MustExec("delete from t")
+	tk.MustExec("insert t values ('str2', 0)")
+	result = tk.MustQuery("select * from t where a = case  when b then 'str3' when 0 then 'str1' else 'str2' end")
+	rowStr2 = fmt.Sprintf("%v %v", []byte("str2"), "0")
+	result.Check(testkit.Rows(rowStr2))
+	tk.MustExec("insert t values ('str1', null)")
+	result = tk.MustQuery("select * from t where a = case b when null then 'str3' when 10 then 'str1' else 'str2' end")
+	result.Check(testkit.Rows(rowStr2))
+	result = tk.MustQuery("select * from t where a = case null when b then 'str3' when 10 then 'str1' else 'str2' end")
+	result.Check(testkit.Rows(rowStr2))
+
 	plan.UseNewPlanner = false
 }