Question

Is there any way to select columns with wild cards.

like

to select columns with names having type could be ‘SELECT %type% from table_name‘ ?

Answer 1

Not really. You can use the * column wildcard to select all columns. If you’re joining multiple tables, you can select all columns from specific table by prefixing * with the table name or alias:

SELECT a.id, a.title, b.*
  FROM articles AS a
    JOIN blurbs AS b ON a.id = b.article

However, you shouldn’t use * unless you’re writing a DB administration program.

Alternatively, you can build a statement within SQL or another language by fetching table metadata to get the column names. Using just MySQL, you can query the COLUMNS table in the INFORMATION_SCHEMA database to get the column names and use GROUP_CONCAT to build the column list for the statement.

SELECT CONCAT(
      'SELECT ',
      GROUP_CONCAT(COLUMN_NAME SEPARATOR ', '),
      ' FROM ', :db, '.', :table,
      ' WHERE ...'
      )
  FROM INFORMATION_SCHEMA.COLUMNS
  WHERE TABLE_SCHEMA=:db AND TABLE_NAME=:table

Replace “:db”, “:table” and “…” with the appropriate values. You can even turn it into a prepared statement so you can use it for any table. From there, PREPARE and EXECUTE the constructed statement.

If you’re not limited to SQL for programming, it should be less messy. The DB driver for your language of choice likely offers methods to get metadata. The actual implementation would be similar to the pure SQL approach (get column names, assemble statement, prepare, execute), but shouldn’t be so ugly, as you’d be using an algorithmic, rather than declarative, language.

I would be very interested in seeing the situation that this is actually required..