Question

I have a table in multi language cms, and I need an UNION SELECT to select tables from all languages, Is anyway that I define the current row is from witch table? something like this:

SELECT *,lan=en FROM en_table UNION SELECT *,lan=fa FROM fa_table ...

I know that I can use this:

SELECT *,(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA = 'db' AND TABLE_NAME = 'en_table' LIMIT 1) As lan FROM en_table UNION ...

but this is stupid idea, is better way for doing this?

Answer 1

Use a string literal enclosed in single quotes, with an alias as in:

SELECT
  *,
  /* string literal 'en' */
  'en' AS lang
FROM en_table
UNOIN ALL
  *,
  /* string literal 'fa' */
  'fa' AS lang
FROM fa_table

Two things to note: It is unwise to use SELECT * in a UNION query. Be explicit about the columns instead, so their order is deterministic.

SELECT
  col1,
  col2,
  'en' AS lang
FROM en_table
UNOIN ALL
  col1,
  col2,
  'fa' AS lang
FROM fa_table

Then, if at all possible, in the long term you should combine all these tables into one, which includes a column identifying the language. That will save you from having to complicate things with UNIONs later on.