Compare structures of two databases?

Question

I wanted to ask whether it is possible to compare the complete database structure of two huge databases. We have two databases, the one is a development database, the other a p

Answer 1

For MySQL database you can compare view and tables (column name and column type) using this query:

SET @firstDatabaseName = '[first database name]';
SET @secondDatabaseName = '[second database name]';

SELECT * FROM  
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @firstDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t1
LEFT JOIN                     
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @secondDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t2 ON t1.tableRowType = t2.tableRowType
WHERE 
  t2.tableRowType IS NULL        
UNION 
SELECT * FROM  
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @firstDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t1
RIGHT JOIN                     
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @secondDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t2 ON t1.tableRowType = t2.tableRowType
WHERE 
  t1.tableRowType IS NULL;

If you prefer using tool with UI you can also use this script https://github.com/dlevsha/compalex which can compare tables, views, keys etc.

Compalex is a lightweight script to compare two database schemas. It supports MySQL, MS SQL Server and PostgreSQL.

Screenshot (compare tables)