If you ever need to use SQL to return just the numeric values in a character column, the method you use will largely depend on your DBMS. Most DBMSs support regular expressions (regex), but some don’t. And some include functions that can detect numeric values.
Here are examples of how to do it in the more popular DBMSs.
Here are examples of using SQL to return duplicate rows when those rows have a primary key or other unique identifier column.
These queries work in most of the major RDBMSs, including SQL Server, Oracle, MySQL, MariaDB, PostgreSQL, and SQLite.
If you have a generated column in PostgreSQL, you can use the following methods to find the definition of that column.
In PostgreSQL, a generated column is a special column that is always computed from other columns. A generated column doesn’t have a fixed value like in a base column. Rather, its value is determined by an expression that references other columns in the table.
Generated columns are included in the SQL standard (ISO/IEC 9075), and are supported by most major RDBMSs. Generated columns were first introduced in PostgreSQL 12.