How to Create a MySQL Event Only if it Doesn’t Already Exist

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In MySQL we can use the CREATE EVENT statement to create scheduled events. As with many CREATE ... statements, we have the option of using the IF NOT EXISTS clause to specify that the object should only be created if it doesn’t already exist.

Of course, we wouldn’t normally be trying to create an event if we know that it already exists. But there may be times where we’re not sure, and we want our code to handle this scenario without throwing an error if an event with the same name already exists. This is common when creating scripts that are designed to be run across multiple environments. That’s where the IF NOT EXISTS clause can come in handy.

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Fix “function array_shuffle(integer) does not exist” in PostgreSQL

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If you’re getting an error that reads “function array_shuffle(integer) does not exist” when using the array_shuffle() function in PostgreSQL, it’s probably because the argument you’re passing to the function is not an array.

More specifically, this error message implies that you’re passing an integer. The same error can occur when passing other non-array types (such as numeric), but the solution is the same.

The argument for this function must be an array.

To fix this error, replace the integer value with an array value when calling the array_shuffle() function.

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Understanding PostgreSQL’s REGEXP_INSTR() Function

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In PostgreSQL, the regexp_instr() function returns the starting or ending position of the N‘th match of a POSIX regular expression pattern to a string. If there’s no match, it returns zero.

We pass the string and pattern as arguments. The function also accepts some optional arguments that allow us to be specific with how the function works.

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A Quick Look at PostgreSQL’s REGEXP_COUNT() Function

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In PostgreSQL, the regexp_count() function returns the number of times a given POSIX regular expression pattern matches in a given string.

We pass the string and pattern as arguments. We can also pass an argument to specify where to start the search. Additionally, we also have the option of specifying a flag that changes the function’s behaviour.

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