Why Does ' ' Fail and '||' Succeed When Concatenating Strings in SQLite?

String Concatenation in SQLite

When performing string manipulation within a SQLite query, users may encounter unexpected results when attempting to concatenate strings using the " " operator. This article aims to shed light on the issue and provide a solution.

Issue Encountered:

Users who try to combine strings using the " " operator in a SQLite query may find that the result is not as expected. For instance, if the following query is executed:

select locationname + '<p>' from location;

instead of obtaining a list of strings consisting of the values in the "locationname" column followed by the literal string "

", the query returns a list of 0s.

Solution:

The key to resolving this issue lies in utilizing the "||" operator instead of the " " operator for string concatenation in SQLite. This is because SQLite treats the " " operator as an addition operator when dealing with strings, resulting in the numeric results seen in the example query.

To achieve the desired concatenation behavior, the following query can be employed:

select locationname || '<p>' from location;

SQLite Documentation Reference:

As per the SQLite documentation:

The || operator is "concatenate" - it joins together the two strings of its operands.

By using the "||" operator, users can successfully concatenate strings in SQLite queries, ensuring accurate results for string manipulations.

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