how to – Page 106

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.

4 Functions to Format a Number to 2 Decimal Places in SQL Server

February 9, 2022 by Ian

When using T-SQL with SQL Server, we can format numbers using various methods, depending on our desired format.

Below are four functions that can be used to format a number to two decimal places in SQL Server.

3 Ways to Find Rows that Contain Lowercase Letters in SQLite

February 9, 2022 by Ian

Here are three options for returning rows that contain lowercase characters in SQLite.

4 Ways to Check for Duplicate Rows in SQL Server

July 23, 2023February 8, 2022 by Ian

Here are four methods you can use to find duplicate rows in SQL Server.

By “duplicate rows” I mean two or more rows that share exactly the same values across all columns.