SQL – Page 20

Concatenate a String and a Number in SQL

November 25, 2021November 24, 2021 by Ian

In most cases, concatenating a string and a number in SQL is no different to concatenating two strings.

Most DBMSs will concatenate the string and number as if they were both strings. This is because the number is usually converted to a string before the concatenation operation.

Add Leading Zeros in SQL

March 11, 2022November 10, 2021 by Ian

Below are examples of adding a leading zero to a number in SQL, using various DBMSs.

Padding in SQL

November 1, 2021 by Ian

Some RDBMSs provide an LPAD() and RPAD() function that enables us to left pad or right pad a string. Some functions also allow us to add leading or trailing zeros numbers.

Below are examples of applying SQL padding in some of the more popular RDBMSs.

How to Concatenate Strings in SQL

October 29, 2021 by Ian

Most of the major RDBMSs provide several options for concatenating two or more strings.

There’s the CONCAT() function, which concatenates its arguments.
There’s also a CONCAT_WS() that allows you to specify a separator that separates the concatenated strings.
And there’s also a string concatenation operator, which allows us to concatenate its operands.

Below are examples of each method.

Get the Month Name from a Date in SQL

October 13, 2021 by Ian

Most major RDBMSs provide at least one function that enables us to return the month name from a date.

Rename a Column in SQL Server (T-SQL)

March 5, 2021 by Ian

In SQL Server, you can use the sp_rename stored procedure to rename an object, including a column.

Join 3 Tables in SQL

July 20, 2024February 19, 2021 by Ian

In SQL, you can join three tables or more by adding another join after the first one.

You can also run nested joins by specifying one join as the join condition for another.

Add a Column to a Table in SQL

February 18, 2021 by Ian

In SQL, you can use the ALTER TABLE statement to add one or more columns to an existing table.

To do this, use the ADD clause, followed by the column definition. Separate multiple columns with a comma.

Only specify ADD once (i.e. there’s no need to specify it for each column).

Create a Relationship in SQL

February 18, 2021February 16, 2021 by Ian

In SQL, you create a relationship by creating a foreign key constraint.

More specifically, you have a parent table and a child table. The parent contains the primary key, and the child table contains a foreign key that references the primary key of the parent table.

When you use SQL to create a relationship, you can create the relationship at the time you create the table, or you can create it later (by altering the table). This article covers both scenarios.

SQL Reference for Beginners

February 18, 2021December 12, 2020 by Ian

This page contains direct links to SQL tutorials and reference articles for beginners.