Below are two methods for returning rows that only contain alphanumeric characters in MariaDB.
Alphanumeric characters are alphabetic characters and numeric characters.
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Fix Error “ORA-01790: expression must have same datatype as corresponding expression”
If you’re getting the error “ORA-01790: expression must have same datatype as corresponding expression” in Oracle Database, it’s probably because you’re using an operator such as UNION, INTERSECT, or EXCEPT to run a compound query, but the columns returned by each query use different data type groups.
To fix this issue, you’ll need to ensure that each column returned by the second query uses the same data type group as the corresponding column in the first query.
Continue reading5 Ways to Select Rows with the Minimum Value for their Group in SQL
Here 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 readingFix Error 1064 (42000) when using the MINUS Operator in MariaDB
There 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.
Continue reading3 Ways to Select the Row with the Minimum Value in SQL
Here are three examples of using SQL to find and select the row with the minimum value in a given column.
The examples work in most major RDBMSs, including MySQL, MariaDB, PostgreSQL, SQLite, Oracle, and SQL Server.
Continue reading6 Ways to Select Duplicate Rows in Oracle
The following examples return duplicate rows from an Oracle Database table.
Continue readingFix “ERROR:Â missing FROM-clause entry for table” in PostgreSQL when using UNION, EXCEPT, or INTERSECT
If you’re getting “ERROR: missing FROM-clause entry for table” in PostgreSQL when using an operator such as UNION, INTERSECT, or EXCEPT, it could be because you’re qualifying a column name with its table name.
To fix this, either remove the table name or use a column alias.
Continue reading4 Ways to Find Rows that Contain Uppercase Letters in Oracle
Here are four options for returning rows that contain uppercase characters in Oracle Database.
Continue readingFix “ERROR:Â each UNION query must have the same number of columns” in PostgreSQL
When using the UNION operator in PostgreSQL, if you encounter an error that reads “ERROR: each UNION 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 UNION operator.
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.
2 Ways to Return Rows that Contain Only Non-Alphanumeric Characters in Oracle
Below are two methods for returning rows that only contain non-alphanumeric characters in Oracle Database.
Alphanumeric characters are alphabetic characters and numeric characters.
Continue reading