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sessionctx: supports set character_set_results = null #7353

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merged 3 commits into from
Aug 11, 2018
Merged

sessionctx: supports set character_set_results = null #7353

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ea2994a
fix issue 7248
Aug 10, 2018
5a827f7
Merge branch 'master' into fix7248
zz-jason Aug 10, 2018
abb812c
Merge branch 'master' into fix7248
coocood Aug 11, 2018
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3 changes: 2 additions & 1 deletion executor/set_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,8 @@ func (s *testSuite) TestSetVar(c *C) {
c.Assert(charset, Equals, "utf8")
c.Assert(collation, Equals, "utf8_bin")

tk.MustExec("set @@character_set_results = NULL")
tk.MustExec("set character_set_results = NULL")
tk.MustQuery("select @@character_set_results").Check(testkit.Rows(""))
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In MySQL, it's very strange that will return NULL instead of "" in select @@ but return "" in show variable orz

mysql> select @@character_set_results ;
+-------------------------+
| @@character_set_results |
+-------------------------+
| utf8                    |
+-------------------------+
1 row in set (0.00 sec)

mysql> set character_set_results = NULL;
Query OK, 0 rows affected (0.00 sec)

mysql> select @@character_set_results ;
+-------------------------+
| @@character_set_results |
+-------------------------+
| NULL                    |
+-------------------------+
1 row in set (0.00 sec)

mysql> show variables where variable_name='character_set_results';
+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| character_set_results |       |
+-----------------------+-------+
1 row in set (0.01 sec)

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I think system variables in MySQL have their own types.


// Test set transaction isolation level, which is equivalent to setting variable "tx_isolation".
tk.MustExec("SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED")
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9 changes: 4 additions & 5 deletions sessionctx/variable/varsutil.go
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Original file line number Diff line number Diff line change
Expand Up @@ -127,12 +127,11 @@ func SetSessionSystemVar(vars *SessionVars, name string, value types.Datum) erro
if sysVar == nil {
return UnknownSystemVar
}
if value.IsNull() {
return vars.deleteSystemVar(name)
}
var sVal string
sVal := ""
var err error
sVal, err = value.ToString()
if !value.IsNull() {
sVal, err = value.ToString()
}
if err != nil {
return errors.Trace(err)
}
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