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.
Here are examples of removing duplicate rows from a table in MariaDB when those rows have a primary key or unique identifier column.
The examples delete duplicate rows but keep one. So in the case of two identical rows, it deletes one of them and keeps the other.
Continue readingBelow are four ways to list out the tables in a MariaDB database using SQL or the command line.
Continue readingIf you have a table that you suspect has duplicate rows in your MariaDB database, you can use any of the following queries to get an idea of how many rows are duplicates.
Continue readingIf you’re getting an error that reads something like “ERROR 1054 (42S22): Unknown column ‘tab.ColName’ in ‘on clause”” in MariaDB, here are three likely causes:
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.
Continue readingIf you’re getting error “ERROR 1054 (42S22): Unknown column ‘colname’ in ‘order clause’” in MariaDB, it may be that you’re trying to reference an aliased column by its column name.
This is a common error when running queries that join two or more tables. It can also happen when using operators such as UNION, INTERSECT, and EXCEPT.
Below are two methods for returning rows that only contain alphanumeric characters in MariaDB.
Alphanumeric characters are alphabetic characters and numeric characters.
Continue readingHere are five options for using SQL to return only those rows that have the minimum value within their group.
These examples work in most major RDBMSs, including MySQL, MariaDB, Oracle, PostgreSQL, SQLite, and SQL Server.
Continue readingThere are at least a few possible reasons you might be getting the dreaded error 1064 (42000) that reads “You have an error in your SQL syntax…” etc when trying to use the MINUS operator in MariaDB.
I’ll explore these below and offer some solutions.
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