how to – Page 106

5 Ways to Select Rows with the Minimum Value for their Group in SQL

July 21, 2023February 16, 2022 by Ian

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.

Fix Error 1064 (42000) when using the MINUS Operator in MariaDB

February 16, 2022 by Ian

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.

3 Ways to Select the Row with the Minimum Value in SQL

February 15, 2022 by Ian

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.

6 Ways to Select Duplicate Rows in Oracle

July 23, 2023February 14, 2022 by Ian

The following examples return duplicate rows from an Oracle Database table.

Fix “ERROR: missing FROM-clause entry for table” in PostgreSQL when using UNION, EXCEPT, or INTERSECT

February 14, 2022 by Ian

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.

4 Ways to Find Rows that Contain Uppercase Letters in Oracle

February 13, 2022 by Ian

Here are four options for returning rows that contain uppercase characters in Oracle Database.

Fix “ERROR: each UNION query must have the same number of columns” in PostgreSQL

February 13, 2022 by Ian

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

February 12, 2022 by Ian

Below are two methods for returning rows that only contain non-alphanumeric characters in Oracle Database.

Alphanumeric characters are alphabetic characters and numeric characters.

7 Ways to Find Duplicate Rows in SQL Server while Ignoring any Primary Key

July 23, 2023February 11, 2022 by Ian

Here are seven options for finding duplicate rows in SQL Server, when those rows have a primary key or other unique identifier column.

In other words, the table contains two or more rows that share exactly the same values across all columns except for its unique identifier column.

Find All Non-Numeric Values in a Column in MariaDB

February 10, 2022 by Ian

If you ever encounter a character column that should be a numeric column, there’s always a possibility that it contains non-numeric data that you don’t know about.

In MariaDB, you can run a query like the following to return non-numeric data from the column.