If you’re getting an error that reads “ERROR 3942 (HY000): Each row of a VALUES clause must have at least one column” in MySQL, you could have an empty row constructor when using the VALUES statement.
To fix this issue, make sure you’ve got at least one value in each ROW() clause within the VALUES statement.
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.
If you’re getting an error that reads something like “ERROR 1136 (21S01): Column count doesn’t match value count at row 2” when using the VALUES statement in MySQL, it’s probably because there’s a mismatch in the number of columns specified in the ROW() clauses.
To fix this error, be sure that all ROW() clauses contain exactly the same number of columns.
When using PostgreSQL’s INTERSECT operator, if you encounter an error that reads “ERROR: each INTERSECT query must have the same number of columns“, it’s because there’s a mismatch in the number of columns returned by the queries on either side of the INTERSECT operator.
The way to fix this is to ensure that both SELECT statements return the same number of columns.
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.
If you’re getting “ERROR: column “colname” does not exist’” in PostgreSQL when using an operator such as UNION, EXCEPT, or INTERSECT, it may be that you’re trying to reference an aliased column by its column name.
If 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:
When using PostgreSQL’s EXCEPT operator, if you encounter an error that reads “ERROR: each EXCEPT query must have the same number of columns“, it’s because there’s a mismatch in the number of columns returned by the queries on either side of the EXCEPT operator.
The way to fix this is to ensure that both SELECT statements return the same number of columns.
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.
Continue readingIf 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.