Most major RDBMSs support the COALESCE() operator, which returns the first non-null value from its list of arguments.
COALESCE() is a SQL-standard feature (it’s included in the ISO/IEC 9075 specification).
SQL
Detect Whether a Value Contains at Least One Numerical Digit in SQL
Sometimes you might need to search a database table for only those rows that contain at least one number in a given column.
Technically, numbers can be represented by words and other symbols, but here “number” means “numerical digit”.
Below are examples of how to find rows that contain at least one number in various SQL based DBMSs.
How to Get Multiple Rows into a Comma Separated List in SQL
Most of the major RDBMSs have a function that enables us to return our query results as a comma separated list.
That is, we can use such a function to convert each row into a separate list item, within a comma separated list.
Below are examples of how to achieve this in some of the more popular RDBMSs.
How to Check a Column’s Data Type in SQL
In SQL, the columns information schema view, which returns information about columns, is an ISO standard view that is supported by most of the major RDBMSs. You can use this view to get information about a column’s data type.
Most of the major RDBMs also provide other methods for getting column information.
Here are examples of getting the data type of a column in various SQL databases.
How to Format Numbers with Commas in SQL
Most of the major RDBMSs have functions that enable us to format numbers with commas as either the group separator, or the decimal separator.
Some RDBMSs also output certain numeric data types with commas in the relevant place.
Below are examples of formatting numbers with commas in some of the more popular DBMSs.
SQL LPAD()
In SQL, LPAD()is a commonly used function that pads the left part of a string with a specified character. The function can be used on strings and numbers, although depending on the DBMS, numbers may have to be passed as a string before they can be padded.
DBMSs that have an LPAD() function include MySQL, MariaDB, PostgreSQL, and Oracle.
DBMSs that don’t have an LPAD() function include SQL Server and SQLite (although there are other ways to apply left padding in these DBMSs).
SQL RPAD()
In SQL, RPAD()is used to pad the right part of a string with a specified character. The function can be used on strings and numbers, although depending on the DBMS, numbers may have to be passed as a string before they can be padded.
DBMSs that have an RPAD() function include MySQL, MariaDB, PostgreSQL, and Oracle.
DBMSs that don’t have an RPAD() function include SQL Server and SQLite.