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*: SubSelect can be used as select statement #350

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merged 4 commits into from
Oct 13, 2015
Merged

*: SubSelect can be used as select statement #350

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*: SubSelect can be used as select statement
shenli Oct 11, 2015
5e56f52
Merge remote-tracking branch 'origin/master' into sheni/issue-320
shenli Oct 12, 2015
abe94aa
parser: Solve merge problem
shenli Oct 12, 2015
522aa0c
tidb: Address comment
shenli Oct 13, 2015
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6 changes: 6 additions & 0 deletions parser/parser.y
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Original file line number Diff line number Diff line change
Expand Up @@ -3437,6 +3437,12 @@ Statement:
| UnionStmt
| UpdateStmt
| UseStmt
| SubSelect
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I think here may be `'(' SelectStmt ')', not SubSelect, in MySQL, SubSelect is not the same as select.
And you can see the MySQL parser that it uses select too, not sub select.

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I tried to add '(' SelectStmt ')' into SelectStmt rule, but I got unresolveable confliction.

{
// `(select 1)`; is a valid select statement
// TODO: This is used to fix issue #320. There may be a better solution.
$$ = $1.(*subquery.SubQuery).Stmt
}

ExplainableStmt:
SelectStmt
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3 changes: 3 additions & 0 deletions parser/parser_test.go
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Expand Up @@ -282,6 +282,9 @@ func (s *testParserSuite) TestDMLStmt(c *C) {
// For show create table
{"show create table test.t", true},
{"show create table t", true},

// For https://github.com/pingcap/tidb/issues/320
{`(select 1);`, true},
}
s.RunTest(c, table)
}
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8 changes: 8 additions & 0 deletions tidb.go
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Expand Up @@ -257,6 +257,14 @@ func trimSQL(sql string) string {
}
break
}
// Trim leading '('. For `(select 1);` is also a query.
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If trim '(', any need to trim ')' suffix?

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No, We judge if the statement is a query only by the prefix

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Then sql will be select 1);
Seems like an invalid sql?

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This is only used to check if sql is query in interpreter. And the trimed sql text will not be used outside this function.

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PTAL @qiuyesuifeng

for {
s := strings.TrimPrefix(sql, "(")
if len(s) == len(sql) {
break
}
sql = s
}
return sql
}

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1 change: 1 addition & 0 deletions tidb_test.go
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Expand Up @@ -300,6 +300,7 @@ func (s *testMainSuite) TestIsQuery(c *C) {
{"/*comment*/ select 1;", true},
{"/*comment*/ /*comment*/ select 1;", true},
{"select /*comment*/ 1 /*comment*/;", true},
{"(select /*comment*/ 1 /*comment*/);", true},
}
for _, t := range tbl {
c.Assert(IsQuery(t.sql), Equals, t.ok, Commentf(t.sql))
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