Sql Server LIKE containing bracket characters
To search for patterns encompassing literal brackets [] in SQL Server, escape them using \. In the LIKE clause, place the escape character before the brackets, and espouse it post pattern with ESCAPE.
In this scenario, \[ finds the [ symbol and \] seeks ], acknowledging them as ordinary characters, rather than wildcards.
With special characters: controlling the chaos
SQL Server's LIKE operator demands mastery over special characters including %, _, [, and ]. The wildcard %, your trusty tool, represents zero or multiples characters, enabling flexible pattern matching. Its ally, _, matches a single character but for your pursuit in accommodating literal characters like brackets, you must skilfully wield the art of escaping.
Employing the ESCAPE clause: taming wildcards
Invoke the ESCAPE keyword to subdue any special character that might disrupt pattern matching. Employing this keyword with a predefined escape character enables you to convert [ or ] from wildcards to simple symbols.
The command above heralds focused search operations while efficiently excluding wildcard perturbations.
Negating without escape in LIKE patterns
Oddly, the rules change when you employ negation patterns with NOT LIKE. Here, [ ] loses its wildcard powers and escapes aren’t necessary.
In this instance, %[%]% is processed as a string, not a pattern seeking any string containing brackets.
Advanced patterns: beyond the brackets
Embrace exclusions with caret
The caret (^), a stalwart in your arsenal, signifies negation when dealing with a character set.
This command excludes any strings containing alphanumeric characters or brackets, reducing the pool to only the exclusivities.
Encountering nested brackets
Nested brackets within a LIKE pattern present moments of complexity. However, a well-defined strategy coupled with an escape character neutralizes such challenges.
This query finds occurrences of the literal string [[%]], a task prone to errors without the ESCAPE clause.
Proactive pattern matching: tips and practices
Specificity: the key to success
While % provides flexibility, sometimes specificity wins. When the need arises to identify a code snippet or symbol within a text block, the LIKE operator empowers you to home in on your target by encapsulating fixed characters with wildcards, striking the bullseye with precision.
Boosting performance through pattern optimization
To retain performance at its peak, effective pattern matching is critical. Starting your pattern with a wildcard (%) can trigger a full table scan, dragging down performance. Whenever possible, affix patterns with leading characters to engage potential indexing, thereby accelerating query execution.
Mastering complexity: collation management
The behaviour of LIKE is influenced by the collation settings of your database or columns. Special characters and case sensitivity can generate varying outcomes, considering whether the collation is case-sensitive (CS) or case-insensitive (CI). Always factor this in to prevent unexpected mismatches.
Was this article helpful?