Understanding String Contains in SQL Server

Welcome Dev, as we delve into the world of SQL Server, it is important to understand the concept of string contains. String contains is a powerful SQL Server function that allows you to search for specific characters or strings within larger strings. In this article, we will explore the ins and outs of string contains and how you can use it to improve your SQL Server queries.

What is String Contains?

String contains is a SQL Server function that allows you to search for a specific string within a larger string. The function returns a boolean value, indicating whether the specified string is contained within the larger string or not.

The syntax for string contains is as follows:

Parameter	Data Type	Description
string_expression	varchar/nvarchar	The string that you want to search
substring_expression	varchar/nvarchar	The string that you want to search for within the larger string

In the next few paragraphs, we will explore the different ways in which you can use string contains in your SQL Server queries.

Using String Contains in WHERE Clauses

One of the most common ways in which you can use string contains is in WHERE clauses. You can use string contains to filter your results based on a specific substring that appears within a larger string.

For example, let’s say you have a table called “Employees” that contains a column called “Full Name”. You can use string contains to find all employees whose full name contains the substring “Smith”. The SQL statement for this would look like:

SELECT * FROM Employees WHERE CONTAINS(FullName, 'Smith');

This SQL statement will return all rows from the Employees table where the FullName column contains the substring “Smith”.

Example:

Let’s say you have the following Employees table:

ID	FullName
1	John Smith
2	Jane Doe
3	Robert Smith
4	Emily Johnson

If you run the following SQL statement:

SELECT * FROM Employees WHERE CONTAINS(FullName, 'Smith');

You will get the following result:

ID	FullName
1	John Smith
3	Robert Smith

Using String Contains in JOIN Clauses

Another way in which you can use string contains is in JOIN clauses. You can use string contains to join two tables based on a specific substring that appears within a larger string.

For example, let’s say you have two tables: “Employees” and “Departments”. The Employees table contains a column called “Department” that specifies the department that each employee belongs to. The Departments table contains a column called “DepartmentName” that specifies the name of each department. You can use string contains to join the two tables based on the department name.

The SQL statement for this would look like:

SELECT * FROM Employees INNER JOIN Departments ON CONTAINS(Employees.Department, Departments.DepartmentName);

This SQL statement will return all rows from the Employees table that have a department name that contains a substring from the Departments table.

Example:

Let’s say you have the following Employees and Departments tables:

ID	FullName	Department
1	John Smith	Accounting
2	Jane Doe	Sales
3	Robert Smith	Human Resources
4	Emily Johnson	Marketing

ID	DepartmentName
1	Accounting
2	Sales
3	HR
4	Marketing

If you run the following SQL statement:

SELECT * FROM Employees INNER JOIN Departments ON CONTAINS(Employees.Department, Departments.DepartmentName);

You will get the following result:

ID	FullName	Department	DepartmentName
1	John Smith	Accounting	Accounting
2	Jane Doe	Sales	Sales
3	Robert Smith	Human Resources	HR
4	Emily Johnson	Marketing	Marketing

Frequently Asked Questions

What is the difference between string contains and like?

The main difference between string contains and like is that string contains is case-sensitive, while like is not. String contains also allows you to search for specific words within a larger string, while like only allows you to search for patterns.

Can I use wildcards with string contains?

No, you cannot use wildcards with string contains. String contains only allows you to search for specific strings within a larger string.

Can I use string contains with multiple substrings?

Yes, you can use string contains with multiple substrings. Simply separate each substring with a logical operator, such as “AND” or “OR”.

Does string contains work with non-English characters?

Yes, string contains works with non-English characters. However, you may need to use the appropriate collation to ensure that the search is performed correctly.

Can I use string contains with numeric data types?

No, you cannot use string contains with numeric data types. String contains only works with character data types, such as varchar and nvarchar.

Can string contains be used to search for words within a sentence?

Yes, string contains can be used to search for specific words within a sentence. Simply enclose the word in quotes to search for an exact match.

Conclusion

String contains is a powerful SQL Server function that allows you to search for specific characters or strings within larger strings. By using string contains, you can filter your results and join tables based on specific substrings that appear within larger strings. While string contains has its limitations, it is an essential tool for any SQL Server developer or administrator. We hope this article has helped you understand the ins and outs of string contains in SQL Server.