how to add a column whose name is a value from another table?? for ex: i've a value for empid:1001 in employee table and i need to add a column in temp table with a column named 1001!!! my actual objective i
PressingTaborEnterwhile the cursor is in the table name field selects theColumnstab of the table editor and creates a default column namedidinvoice. PressingTaborEnteragain sets the focus on theDatatypelist withINTselected. Notice that a field has been added to the table on the EER canvas. P...
The reason for this is that the anonymous-user account has a more specific Host column value than the 'finley'@'%' account and thus comes earlier in the user table sort order. (For information about user table sorting, see Section 4.5, “Access Control, Stage 1: Connection Verification”....
1 row in set, 1 warning (0.00 sec) A conclusionfrom this is we want smallerprimary keys if possible. ’s this table accordingly 1 2 3 mysql> alter tablet1 drop primarykey, column idint primarykey autoincrement; QueryOK, 0 rows affected(16.66 sec) Records: 0 Duplicates...
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to add another unique column to act as the primary key. The internal GEN_CLUST_INDEX one is not exposed to the upper MySQL layer, and only theInnoDB engine is aware of it, hence it is useless for replication speed. Therefore, an explicit PK is always a better solution. However, if...
But if that’s not an option (say your client’s support contract only covers MySQL), there’s still a way to write your migrations such that Postgres, SQLite, and MySQL all behave in the same correct way when adding NOT NULL columns to existing tables: add the column first, then add...
I have a MySQL db, and one of the tables has a JSON blob in it, with a virtual column generated from that JSON content. CREATE TABLE `my_table` ( `name` varchar(50) NOT NULL, `json` json DEFAULT NULL, `virtual_column` bigint(20) GENERATED ALWAYS AS (json_unquote(json_extract(`...
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I need to add a column (say new_position) to an already created table, which i can do so by using alter table. The problem is actually inserting values into new_position. the values in this column should be 23+value from another column (say position) which itself is a column in the...