Why Does My Postgresql Query Return a 'Column Name Does Not Exist' Error?

Troubleshooting "Column Name Does Not Exist" Error in Postgresql Queries

In working with Postgresql databases, it's crucial to adhere to proper syntax and naming conventions to avoid errors. One common challenge is encountering the "column name does not exist" error during query execution.

Consider the following query:

SELECT * 
FROM employee 
WHERE "lName" LIKE "Smith"

When executing this query, you might receive an error stating that the column "Smith" does not exist. This is because Postgresql interprets "Smith" within double quotes as an identifier (column name), not a string.

To resolve this issue, the double quotes should be replaced with single quotes to denote a string literal:

SELECT * 
FROM employee 
WHERE "lName" LIKE 'Smith'

Now, Postgresql will recognize "Smith" as a value to be matched against the "lName" column, which is correctly quoted.

Additionally, it's important to ensure that the column name in the WHERE clause matches the actual column name in the database table. In this case, the table contains a column named "lName" with an uppercase "N". Therefore, it must be quoted in the query to distinguish it from other potential column names.

Finally, consider whether you intended to include a wildcard in the LIKE clause. In most SQL dialects, using LIKE without a wildcard (e.g., "Smith") is equivalent to using =. If you meant to search for partial matches, you should include a wildcard, such as:

SELECT * 
FROM employee 
WHERE "lName" LIKE '%Smith%'

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