锁定表以读取 MYSQL

Question

I want to lock a particular table for reading but when I queried

   mysql_query("LOCK TABLES unique_voucher READ");

into the database it allows me to read only this table but not the other tables.

Is it possible to lock this particular table ONLY and does not allow the users to query this table until some process is finished?

(this is because i am holding a counter and if a lot of users connect at once they can get ambiguous numbers, so until one user is ready with once process I want to lock the reading for a table)

Answer 1

If you share the same DB connection for all users, one possible solution is to lock all other tables, except the one you want. The locked tables will be available.

From http://dev.mysql.com/doc/refman/5.0/en/lock-tables.html :

"A session that requires locks must acquire all the locks that it needs in a single LOCK TABLES statement. While the locks thus obtained are held, the session can access only the locked tables . For example, in the following sequence of statements, an error occurs for the attempt to access t2 because it was not locked in the LOCK TABLES statement:"

mysql> LOCK TABLES t1 READ;
mysql> SELECT COUNT(*) FROM t1;
+----------+
| COUNT(*) |
+----------+
|        3 |
+----------+
mysql> SELECT COUNT(*) FROM t2;
ERROR 1100 (HY000): Table 't2' was not locked with LOCK TABLES