Differences Between SQL and T-SQL: A Detailed Comparison


If you are just starting to study SQL, this article will help clear up any confusion you may have regarding the differences between standard SQL and other languages like T-SQL. Along with understanding how SQL and T-SQL vary from one another, you’ll also discover which topics and explanations you should learn first.

Here, we will also focus on the syntax differences between SQL and T-SQL along with proper examples. If you believe T-SQL is merely an extension of regular SQL that implements all its features, you need to know a lot. This article will help you gain that information.

What is SQL?

Structured Query Language, known simply as “SQL,” belongs to the category of programming languages known as query languages. It is a fundamental ANSI/ISO standard programming language designed to operate on data stored in databases. Data selection, manipulation, object creation, user management, and database management are all possible with SQL. It is also used for adding, retrieving, or updating data stored in any database. It is used across many various types of databases.

What is T-SQL or Transact-SQL?

Transact-SQL, or T-SQL, is an extension of the SQL language that is mostly used with Microsoft SQL Server. This indicates that it offers all of SQL’s features along with some additional ones. Compared to what the SQL standard specifies, T-SQL provides more features and functions. As standard SQL contains practically all of the functionality of T-SQL, if you are familiar with T-SQL you are also familiar with standard SQL. So basically, the key distinction between SQL and T-SQL is that the latter offers more capabilities designed to make developing queries simpler, faster, and more effective. T-SQL is therefore used if you operate with MS SQL Service.

In other relational database systems, the extension names and functionalities are different. For example, PostgreSQL implements PL/pgSQL, and Oracle has the PL/SQL language.

What is the difference between SQL and T-SQL?

After going through the fundamentals of both, let’s first look at their primary key differences and then we will see some syntax differences between SQL and T-SQL:

1. Language

While SQL is the structured query language that can specifically be used for executing a query with various operations like insert, update, delete, and select in which the user cannot execute multiple statements at once, T-SQL is the transactional structured query language that can be used in SQL programming for various transactional activities. When the user is able to use T-SQL, they are able to utilize various programming techniques.

2. Standards

The Structured Query Language, or SQL, is standardized by ANSI/ISO, while the SQL language’s implementation, T-SQL, also adheres to SQL. SQL is a standardized language that can be used with any RDBMS that supports SQL. IBM has developed SQL. T-SQL, on the other hand, is specific to Microsoft’s SQL Server database software.

3. Usage

While SQL statements have been used for generating periodic reports, web pages, and screens, and it helps for assisting the applications if we want to do updates in application logic, T-SQL has been used for executing the backend transactions of the application with the help of various programming techniques, and in particular, it has been used for adding business logic in a fixed programme.

4. Objects

While SQL has been used for interaction by using DDL and DML statements, T-SQL has been used to create the procedures, functions, and triggers, which are referred to as objects.

5. Database

Let’s talk about how SQL and T-SQL may instruct the database. T-SQL is a transactional language that instructs the database on how to carry out certain tasks. The declarative statements in SQL, in contrast, inform the database what to do but cannot specify how to carry out the actions.

6. Execution

One SQL statement is run at a time, which is referred to as “non-procedural.” T-SQL runs statements in a “procedural” manner, which refers to the processing of the code as a block, logically, and in a predetermined order.

7. Operating on Strings

Another distinction between the SQL standard and T-SQL is how functions are used to manipulate strings. In SQL, you can concatenate strings using the ‘||‘ operator or the CONCAT() function whereas in T-SQL, you can use the ‘+' operator to concatenate strings. T-SQL uses the LEN() function to return the length of a string, whereas standard SQL uses the LENGTH() function. Another difference is that Regular expressions are supported by T-SQL’s LIKE operator and PATINDEX() function. On the other hand, Regular expressions are not supported natively by SQL, but you can get around this by using third-party libraries or user-defined functions. In general, T-SQL provides more advanced string manipulation features than SQL with differences in parameters and syntaxes between the two languages.

8. Incorporating both SQL and T-SQL

The T-SQL code cannot be inserted into the SQL, but we can integrate the SQL into the T-SQL.

9. AGGREGATE Functions

Using the aggregate functions, we notice still another syntax variation. A count-related input is required for the use of the functions COUNT, SUM, and AVG. T-SQL permits the use of DISTINCT before these parameter values, ensuring that only rows are counted if the values differ from those of other rows. DISTINCT cannot be used in these functions according to the SQL standard.

Standard SQL:
SELECT COUNT(DISTINCT col) FROM table;Code language: SQL (Structured Query Language) (sql)

10. INEQUALITY Operator

Sometimes an Inequality operator is required when filtering records in a SELECT statement. Standard SQL defines ‘<>’ as this operator, while T-SQL supports both the regular operator and the ‘!=‘ operator.

SELECT col3 FROM tab WHERE col1 != col2

11. MATH Functions

The SQL standard includes a number of widely used mathematical functions. These mathematical operations include CEIL(x), which is absent from T-SQL. T-SQL offers the following non-standard functions as an alternative: To round a decimal value x to the specified number of decimal positions, use SIGN(x), ROUND(x,[,d]), TRUNC(x), to return the natural logarithm of a value x, use LOG(x), and generate random numbers using RANDOM(). The MAX(list) and MIN(list) methods in the SQL standard return the highest or lowest value in a list, however, in Transact-SQL you use the GREATEST(list) and LEAST(list) functions. For example,

T-SQL function ROUND:
SELECT ROUND(col)  FROM table;Code language: SQL (Structured Query Language) (sql)

12. Retrieving Parts of Date and Time

The majority of relational database systems include a wide range of functions to work with dates and times. In standard SQL, the EXTRACT(YEAR FROM x) function and functions similar to select parts of dates are different from the T-SQL functions like YEAR(x) or DATEPART(year, x).

13. The OUTPUT Keyword

The DELETE, UPDATE, and INSERT statements all contain the OUTPUT keyword. It isn’t specified in conventional SQL. We can view additional data returned by a query using T-SQL. The values added using INSERT or deleted using DELETE, or both old and new values in UPDATE, are returned. Prefixes in INSERT, UPDATE, and DELETE must be used in order to display this information.

UPDATE table SET col='new_value' 
OUTPUT  Deleted.col, Inserted.colCode language: SQL (Structured Query Language) (sql)

The outcome of updating records is displayed in an updated column containing the old and new values. This functionality is not supported by the SQL standard.

Which is better to learn SQL or T-SQL?

Learning SQL is a requirement if you want to work with databases in any way or if you’re looking for a job in the data industry. Since T-SQL is an extension of SQL, you must first become familiar with the fundamentals of SQL. If you first learn T-SQL, you will eventually learn conventional SQL as well.

The majority of the time, what you choose to learn should be based on your goals. It is worthwhile to understand more about T-SQL if you plan to work with a Microsoft SQL server. Learn about SQL first if you’re a beginner trying to get started utilising databases.

Also Read: Is it Difficult to Learn SQL?


The basic changes in syntax between T-SQL and SQL are addressed in this article. This article does also assist in highlighting several fundamental aspects that are unique to Transact-SQL and what SQL standard does not provide.

If you ultimately choose to go with SQL, we have a tutorial on the most important SQL query for beginners that can help you get started.