Best way to add a column in mysql query

Can any one please let me know that, I need to add a column dynamically when executing mysql query

Table: Table1
----------------开发者_JS百科----------
col1      col2       col3
--------------------------
Test      OK       Test3
Test      OK       Test5
Test      OK       Test6

from the above example i need to introduce "col2" as new column and its value to be as "OK"

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select a constant value and give it an alias.

SELECT `col1`, 'OK' AS `col2`, `col3`
FROM `table1`

but why do you need to do this in mysql? if the value is the same for every row, you can just as easy add it in your client (php or similar) code

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You can use this but make sure that database user has the permission to alter table

ALTER TABLE `Table1` ADD `Col2` DEFAULT 'ok' AFTER `Col1`