func (s *testEvaluatorSuite) TestEvaluatedFlag(c *C) {
l := ast.NewValueExpr(int64(1))
r := ast.NewValueExpr(int64(2))
b := &ast.BinaryOperationExpr{L: l, R: r, Op: opcode.Plus}
ast.SetFlag(b)
c.Assert(ast.IsPreEvaluable(b), Equals, true)
d, err := Eval(s.ctx, b)
c.Assert(ast.IsEvaluated(b), Equals, true)
c.Assert(err, IsNil)
c.Assert(d, testutil.DatumEquals, types.NewIntDatum(3))
funcCall := &ast.FuncCallExpr{
FnName: model.NewCIStr("abs"),
Args: []ast.ExprNode{ast.NewValueExpr(int(-1))},
}
b = &ast.BinaryOperationExpr{L: funcCall, R: r, Op: opcode.Plus}
ast.ResetEvaluatedFlag(b)
ast.SetFlag(b)
c.Assert(ast.IsPreEvaluable(b), Equals, true)
d, err = Eval(s.ctx, b)
c.Assert(ast.IsEvaluated(b), Equals, false)
c.Assert(err, IsNil)
c.Assert(d, testutil.DatumEquals, types.NewIntDatum(3))
rf := &ast.ResultField{Expr: ast.NewValueExpr(int64(1))}
colExpr := &ast.ColumnNameExpr{Refer: rf}
b = &ast.BinaryOperationExpr{L: colExpr, R: r, Op: opcode.Plus}
ast.ResetEvaluatedFlag(b)
ast.SetFlag(b)
c.Assert(ast.IsPreEvaluable(b), Equals, false)
d, err = Eval(s.ctx, b)
c.Assert(ast.IsEvaluated(b), Equals, false)
c.Assert(err, IsNil)
c.Assert(d, testutil.DatumEquals, types.NewIntDatum(3))
}
// Build builds a prepared statement into an executor.
func (e *ExecuteExec) Build() error {
vars := variable.GetSessionVars(e.Ctx)
if e.Name != "" {
e.ID = vars.PreparedStmtNameToID[e.Name]
}
v := vars.PreparedStmts[e.ID]
if v == nil {
return ErrStmtNotFound
}
prepared := v.(*Prepared)
if len(prepared.Params) != len(e.UsingVars) {
return ErrWrongParamCount
}
for i, usingVar := range e.UsingVars {
val, err := evaluator.Eval(e.Ctx, usingVar)
if err != nil {
return errors.Trace(err)
}
prepared.Params[i].SetDatum(val)
}
ast.ResetEvaluatedFlag(prepared.Stmt)
if prepared.SchemaVersion != e.IS.SchemaMetaVersion() {
// If the schema version has changed we need to prepare it again,
// if this time it failed, the real reason for the error is schema changed.
err := plan.PrepareStmt(e.IS, e.Ctx, prepared.Stmt)
if err != nil {
return ErrSchemaChanged.Gen("Schema change casued error: %s", err.Error())
}
prepared.SchemaVersion = e.IS.SchemaMetaVersion()
}
sb := &subqueryBuilder{is: e.IS}
p, err := plan.Optimize(e.Ctx, prepared.Stmt, sb, e.IS)
if err != nil {
return errors.Trace(err)
}
b := newExecutorBuilder(e.Ctx, e.IS)
stmtExec := b.build(p)
if b.err != nil {
return errors.Trace(b.err)
}
e.StmtExec = stmtExec
e.Stmt = prepared.Stmt
return nil
}
func (s *testEvaluatorSuite) TestCaseWhen(c *C) {
defer testleak.AfterTest(c)()
cases := []testCase{
{
exprStr: "case 1 when 1 then 'str1' when 2 then 'str2' end",
resultStr: "str1",
},
{
exprStr: "case 2 when 1 then 'str1' when 2 then 'str2' end",
resultStr: "str2",
},
{
exprStr: "case 3 when 1 then 'str1' when 2 then 'str2' end",
resultStr: "<nil>",
},
{
exprStr: "case 4 when 1 then 'str1' when 2 then 'str2' else 'str3' end",
resultStr: "str3",
},
}
s.runTests(c, cases)
// When expression value changed, result set back to null.
valExpr := ast.NewValueExpr(1)
whenClause := &ast.WhenClause{Expr: ast.NewValueExpr(1), Result: ast.NewValueExpr(1)}
caseExpr := &ast.CaseExpr{
Value: valExpr,
WhenClauses: []*ast.WhenClause{whenClause},
}
ctx := mock.NewContext()
v, err := Eval(ctx, caseExpr)
c.Assert(err, IsNil)
c.Assert(v, testutil.DatumEquals, types.NewDatum(int64(1)))
valExpr.SetValue(4)
ast.ResetEvaluatedFlag(caseExpr)
v, err = Eval(ctx, caseExpr)
c.Assert(err, IsNil)
c.Assert(v.Kind(), Equals, types.KindNull)
}