operators – Page 5

SQLite -> Operator

April 3, 2022April 3, 2022 by Ian

In SQLite, the -> operator extracts a subcomponent from a JSON document and returns a JSON representation of that subcomponent.

The -> operator was first introduced in SQLite version 3.38.0 (released on 22 February 2022).

Fix “ERROR 1222 (21000): The used SELECT statements have a different number of columns” when using UNION in MariaDB

March 25, 2022 by Ian

When using the UNION operator in MariaDB, you may encounter the following error: “ERROR 1222 (21000): The used SELECT statements have a different number of columns”.

This error occurs when the number of columns returned by each SELECT statement is different.

The way to fix this is to ensure that both SELECT statements return the same number of columns.

SQLite Introduces the -> and ->> Operators for Extracting JSON Subcomponents

April 3, 2022March 19, 2022 by Ian

Starting with SQLite version 3.38.0 (released on 22 February 2022), we can now use the -> and ->> operators to extract subcomponents of JSON documents.

The aim with these operators is to be compatible with the equivalent MySQL and PostgreSQL operators.

Fix “ERROR 1222 (21000): The used SELECT statements have a different number of columns” when using UNION in MySQL

March 12, 2022 by Ian

If you’re getting “ERROR 1222 (21000): The used SELECT statements have a different number of columns” when using the UNION clause in a MySQL query, it’s probably because the number of columns returned by each SELECT statement is different.

Fix “ERROR 1250 (42000): Table ‘…’ from one of the SELECTs cannot be used in global ORDER clause” when using UNION in MySQL

September 17, 2023March 4, 2022 by Ian

If you’re getting an error that reads “ERROR 1250 (42000): Table ‘…’ from one of the SELECTs cannot be used in global ORDER clause” when using the UNION clause in a MySQL query, it’s probably because you’re qualifying a column name with its table name.

This doesn’t work in MySQL.

To fix this issue, either remove the table name or use a column alias.

Fix “ERROR 1054 (42S22): Unknown column ‘…’ in ‘order clause'” when using UNION in MySQL

September 17, 2023February 28, 2022 by Ian

If you’re getting error “1054 (42S22): Unknown column ‘…’ in ‘order clause'” when using the UNION clause in MySQL, it could be because you’re trying to reference an aliased column by its column name.

Fix “ERROR 1250 (42000): Table ‘…’ from one of the SELECTs cannot be used in ORDER clause” in MariaDB

September 17, 2023February 25, 2022 by Ian

If you’re getting “ERROR 1250 (42000): Table ‘…’ from one of the SELECTs cannot be used in ORDER clause”, it’s probably because you’re qualifying a column name with its table name when using an operator such as UNION, INTERSECT, or EXCEPT in MariaDB.

To fix this, either remove the table name or use a column alias.

SQLite INTERSECT Operator

February 22, 2022 by Ian

In SQLite, the INTERSECT operator is used to create a compound SELECT statement that returns the intersection of the results of the left and right SELECT statements. In other words, it combines two queries, but returns only those rows that are returned in both queries.

SQLite EXCEPT Operator

February 21, 2022 by Ian

In SQLite, the EXCEPT operator can be used to create a compound SELECT statement that returns the subset of rows returned by the left SELECT that are not returned by the right SELECT.

SQLite UNION Operator

February 20, 2022 by Ian

In SQLite, the UNION operator creates a compound SELECT statement that returns the results of the left and right SELECT statements. In other words, it combines the results from two queries into a single result set.