Check if Table Exists in SQL

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With SQL we can use various methods to check whether or not a table (or other object) exists in the database. The method we use will often depend on the RDBMS we’re using, as well as the task we’re trying to undertake.

There’s usually a reason we’re trying to check for the existence of a table, and often the syntax we use will be tied to that reason. For example the ...IF EXISTS clause is a handy addition to the DROP TABLE statement, and the ...IF NOT EXISTS clause can often be used with the CREATE TABLE statement.

Other times we may simply want to see if the table exists without performing any immediate actions against that table. In such cases, we would need to run code specifically to see if the table exists.

Below are examples of code we can use in each of the above scenarios.

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Using VALUES as a Stand Alone Statement in MySQL

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MySQL 8.0.19 introduced the VALUES DML statement, which is a table constructor that can be used as a stand alone SQL statement.

This is not to be confused with the VALUES keyword that’s used with the INSERT or REPLACE statements when inserting data (although it can be used for that purpose too). It also shouldn’t be confused with the VALUES() function that’s used with INSERT … ON DUPLICATE KEY UPDATE statements.

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Fix “Window element in OVER clause can not also be specified in WINDOW clause” in SQL Server

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If you’re getting error number 4123 that reads “Window element in OVER clause can not also be specified in WINDOW clause” in SQL Server, it’s probably because you’re referring to a named window with the same clause that’s in the named window.

When we use the OVER clause to refer to a named window in SQL Server, we can’t include a clause that’s also present in the named window.

To fix the issue, remove one of the clauses – either the one in the OVER clause or the one in the named window.

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Using Fractions when Generating a Series in SQL Server

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When we use SQL Server’s GENERATE_SERIES() function to create a series, we provide the start and stop points as numbers. And if we provide the optional step argument, then it’s provided as a number too.

The numbers we provide can be decimal fractions if required. This means that we can create a series made up of decimal fractions. But we still need to ensure that all our arguments are of the same type.

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Fix “Procedure or function GENERATE_SERIES has too many arguments specified” in SQL Server

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If you’re getting error 8144 with a message that reads “Procedure or function GENERATE_SERIES has too many arguments specified” in SQL Server, it’s because you’re passing too many arguments to the GENERATE_SERIES() function.

The GENERATE_SERIES() function/relational operator accepts a minimum of two arguments, and a maximum of three (at least, this is the case at the time of writing).

So to fix this error, be sure to provide either two arguments or three when using the GENERATE_SERIES() function.

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Creating Named Windows in SQL Server with the WINDOW Clause

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Many RDBMSs support the concept of named windows – windows that we can reference from within an OVER clause when defining a window function.

For those of us using SQL Server, we had to wait until the release of SQL Server 2022 before we could create named windows for our window functions. But with the release of SQL Server 2022, we now have the option of using named windows in our window functions.

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