functions – Page 39

About the JSON_MERGE() Function in MySQL

June 28, 2023April 13, 2023 by Ian

In MySQL, JSON_MERGE() is a deprecated function that merges two or more JSON documents and returns the result.

It was deprecated in MySQL 8.0.3 and is subject to removal in a future release.

Fortunately, the JSON_MERGE_PRESERVE() function was added in MySQL 8.0.3 as a synonym for JSON_MERGE(), and it therefore does the same thing that JSON_MERGE() does/did.

Therefore, instead of using JSON_MERGE(), use JSON_MERGE_PRESERVE() instead.

Alternatively, you can use JSON_MERGE_PATCH(), which performs an RFC 7396 compliant merge of two or more JSON documents, without preserving members having duplicate keys.

How JSON_TABLE() Works in MySQL

April 11, 2023 by Ian

In MySQL, JSON_TABLE() is a built-in function that converts JSON data into a relational form.

In other words, it lets you return a JSON document as a table.

The JSON_TABLE() function was introduced in MySQL 8.0.

How CAST() Works in MySQL

April 5, 2023 by Ian

In MySQL, CAST() is a built in function that converts a value to another data type. It takes a value of one type and returns a value of the specified type.

You provide the value as an argument when you call the function, as well as the type that you’d like it converted to.

CAST() works similar to CONVERT(), except that the syntax used is slightly different.

How LAST_INSERT_ID() Works in MySQL

June 10, 2023March 31, 2023 by Ian

In MySQL, the LAST_INSERT_ID() function returns the first automatically generated value successfully inserted for an AUTO_INCREMENT column as a result of the most recently executed INSERT statement.

It can also be called with an argument, in which case, it returns the value of the expression and the next call to LAST_INSERT_ID() will return the same value.

How GENERATE_SERIES() Works in PostgreSQL

April 27, 2024March 28, 2023 by Ian

In PostgreSQL, we can use the generate_series() function to return a series of values between a given start and stop point. This can be a series of numbers or a series of timestamps.

The function returns a set containing the series.

MySQL ICU_VERSION() Explained

March 27, 2023 by Ian

In MySQL, the ICU_VERSION() function returns the version of the International Components for Unicode (ICU) library used to support regular expression operations.

The ICU_VERSION() function is primarily intended for use in test cases.

How CURRENT_ROLE() Works in MySQL

March 23, 2023 by Ian

In MySQL, CURRENT_ROLE() is a built-in function that returns the current active roles for the current session, separated by commas, or NONE if there are none. The current role determines our access privileges.

MySQL COERCIBILITY() Explained

March 21, 2023 by Ian

In MySQL, the COERCIBILITY() returns the collation coercibility value of its string argument.

The COERCIBILITY() function defines how collations will be converted in the case of collation conflict. In such conflicts, an expression with a higher coercibility is converted to the collation of an expression with a lower coercibility.

How CONNECTION_ID() Works in MySQL

March 18, 2023 by Ian

The MySQL CONNECTION_ID() function returns the connection ID (thread ID) for the connection.

In MySQL, every connection has an ID that is unique among the set of currently connected clients. We can use the CONNECTION_ID() function to return that ID.

How SETVAL() Works in PostgreSQL

March 16, 2023 by Ian

In PostgreSQL, we can use the setval() function to set a sequence’s value.

We specify the value when we call the function. We also have the option of setting its is_called flag.