Mysql "IF" in query

Question

I have few tables

table201202
table201203
table201204
table201205  
...
tableversion

In tableversion I have columns: Version_ID Admin_ID MONTH YEAR

I need to get something like this

Select *
FROM tableversion
LEFT JOIN table(tableversion.month tableversion.year) on
    table(tableversion.month tableversion.year).Version_ID=tableversion.version_id

But in tableversion I've got months without leading 0 so i must check if there is 5 and then change it to 05, if variable is 12 then nothing. How can I do it?

Ok, so now i have something like this

SELECT *, CONCAT('table',IF(tableversion.month < 10, CONCAT('0', tableversion.month ), tableversion.month ),year) as year
FROM tableversion
LEFT JOIN year ON tableversion.version_id=year.version_id WHERE ADMIN_ID=11

#1146 - Table 'database.year' doesn't exist

But it does not work

Answer 1

I think an IF statement would likely perform poorly, but I have no data to back that claim.

You can try this alternative to an IF statement to achieve the same: SELECT *, LPAD(month, 2, '0') as month2 ....

Answer 2

As seen here, use LPAD:

SELECT LPAD(month,2,'0') ...

Answer 3

Try this out in the area where you're concerned about comparing the months

IF(tableversion.month < 10, CONCAT('0', tableversion.month), tableversion.month)