show global variables where syntax is broken

[Lee Bieber]

Found this in variables.test

drizzle> show global variables like 'warning_count';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| warning_count | 0 |
+---------------+-------+
1 row in set (0.01 sec)

drizzle> show global variables where Variable_name='warning_count';
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your Drizzle server version for the right syntax to use near 'where Variable_name='warning_count'' at line 1

I've commented out this test for now, please un-comment once this bug is fixed.

[Padraig O'Sullivan (posulliv)]

I was able to verify this behavior:

drizzle> show global variables like 'warning_count';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| warning_count | 0 |
+---------------+-------+
1 row in set (0.00 sec)

drizzle> show global variables where Variable_name = 'warning_count';
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your Drizzle server version for the right syntax to use near 'where Variable_name = 'warning_count'' at line 1
drizzle>

Thanks, Padraig.

[Padraig O'Sullivan (posulliv)]

The fix for this turns out to be pretty simple - we just need to either add a new rule to sql_yacc or modify the existing one that is used for SHOW commands. For example, we can change this:

show_wild:
          /* empty */
        | LIKE TEXT_STRING_sys
          {
            Lex->wild= new (YYSession->mem_root) String($2.str, $2.length,
                                                    system_charset_info);
          }

to this (or we could add a new rule instead of modifying the existing one):

show_wild:
          /* empty */
        | LIKE TEXT_STRING_sys
          {
            Lex->wild= new (YYSession->mem_root) String($2.str, $2.length,
                                                    system_charset_info);
          }
        | WHERE expr
          {
            Select->where= $2;
            if ($2)
              $2->top_level_item();
          }
        ;

and it works fine as shown here:

posulliv@aghadoe:~/repos/drizzle/local-build/tests$ ../client/drizzle --port=9306
Welcome to the Drizzle client.. Commands end with ; or \g.
Your Drizzle connection id is 2
Server version: 2009.06.1055-local-build Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

drizzle> show global variables where variable_name = 'warning_count';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| warning_count | 0 |
+---------------+-------+
1 row in set (0.05 sec)

drizzle>

However, I'm wondering if this is wanted? Was this functionality removed for a reason and do we want to put it back in? I don't know what the original reason for removing this functionality is so I can't comment. If this functionality is wanted, I can push the fix pretty quickly and propose a merge.

[Jay Pipes (jaypipes)]

Sure, this looks good. Not sure why this was removed....

[Padraig O'Sullivan (posulliv)]

Ok, I proposed a branch for merging with this fix in it.