Articles

PostgreSQL Error 22P02: Invalid Text Representation

Fix PostgreSQL SQLSTATE 22P02 by checking the target type, empty strings, numeric values, and date formats before casting.

PostgreSQL Error 42704: Object Does Not Exist

Troubleshoot PostgreSQL SQLSTATE 42704 by checking the current database, schema search_path, quoted names, and object definitions.

PostgreSQL Error 42803: Grouping Error

Fix PostgreSQL SQLSTATE 42803 by grouping selected columns correctly, aggregating them, or using the supported primary-key dependency.

PostgreSQL Error 42804: Datatype Mismatch

Troubleshoot PostgreSQL SQLSTATE 42804 in INSERT, UPDATE, UNION, CASE, and VALUES by comparing expression and column types.

PostgreSQL Error 42883: Function Does Not Exist

Troubleshoot PostgreSQL SQLSTATE 42883 by checking function names, schemas, search_path, argument types, and procedure calls.

2 Ways to List Stored Procedures in MySQL

List MySQL stored procedures with SHOW PROCEDURE STATUS or INFORMATION_SCHEMA.ROUTINES, filter by database, and understand privilege limits.

3 Ways to Find a Substring's Position in MySQL

Compare MySQL LOCATE(), INSTR(), and POSITION() to find a substring’s 1-based position, including argument order and start-position behavior.

3 Ways to Get the First Day of the Month in MySQL

Get the first day of the current or a specified month in MySQL with DATE_SUB(), DATE_FORMAT(), or LAST_DAY().

4 Ways to Find Duplicate Rows in MySQL

Find duplicate MySQL values with GROUP BY and HAVING, return matching rows, count duplicates with a window function, or identify extra rows with ROW_NUMBER().

4 Ways to Replace NULL with a Different Value in MySQL

Compare MySQL COALESCE(), IFNULL(), IF(), and CASE for returning a fallback value when an expression is NULL.