SQL Batch Queries refer to groups of one or more Transact-SQL (T-SQL) statements that are sent to and executed by SQL Server as a single unit. In SQL Server 2022, batch processing remains a fundamental concept for query execution and optimization.
Key Characteristics of SQL Batch Queries
-
Definition:
- A batch is a set of SQL statements submitted together and parsed/executed as a unit
- Batches are separated by the
GO
statement in tools like SSMS (though GO
is not a T-SQL command)
-
Execution Context:
- Each batch runs in a single execution context
- Variables declared in one batch aren't visible to subsequent batches
- Errors may affect batch execution differently depending on severity
SQL Server 2022 Enhancements for Batch Processing
- Intelligent Query Processing (IQP) Improvements:
- Enhanced batch mode memory grant feedback
- Improved batch mode adaptive joins
- Degree of Parallelism (DOP) feedback for batch mode operations
- Parameter Sensitive Plan (PSP) Optimization:
- Better handling of batches with parameterized queries that have varying cardinality
- Memory-Optimized TempDB Metadata:
- Improved performance for batches that heavily use temporary tables
-- Batch 1: Creates a table and inserts data
CREATE TABLE dbo.Customers (
CustomerID INT PRIMARY KEY,
Name NVARCHAR(100)
);
INSERT INTO dbo.Customers VALUES (1, 'John Doe');
GO -- Signals end of batch
-- Batch 2: Queries the table (can't see variables from Batch 1)
SELECT * FROM dbo.Customers;
GO
Best Practices for Batch Queries in SQL Server 2022
- Transaction Management:
- Group related operations in the same batch when they should succeed or fail together
- Be aware that batches don't automatically imply transactions
- Error Handling:
- Use TRY/CATCH blocks within batches for comprehensive error handling
- Understand that compilation errors prevent the entire batch from executing
- Performance Considerations:
- Large batches can reduce network round trips but may increase memory usage
- Consider using table-valued parameters for batch data operations
- Leverage batch mode execution for analytical workloads
- Security:
- Use parameterized batches to prevent SQL injection
- Consider the EXECUTE AS clause for specific permission contexts
Batch vs. Transaction
Important distinction:
- Batch: A group of statements sent to the server together
- Transaction: A logical unit of work that must be completed as a whole (using BEGIN TRANSACTION, COMMIT, ROLLBACK)
To send SQL
batch[1] statements all at once for execution in SQL Server Management Studio (SSMS), you can follow these steps:
β
What is a SQL Batch Statement?
A batch is a group of one or more T-SQL statements sent to SQL Server for execution as a unit. Batches are separated by the `GO` keyword in SSMS.
π§ Steps to Execute SQL Batch Statements in SSMS
-
Open SSMS and Connect to a Server
- Launch SSMS
- Connect to your SQL Server 2022 instance
-
Open a New Query Window
- Click
New Query
in the toolbar
- Make sure the correct database is selected from the dropdown
-
Enter Your SQL Batch Script
USE AdventureWorks2022;
GO
CREATE TABLE dbo.TestBatch (
Β Β ID INT PRIMARY KEY,
Β Β Name NVARCHAR(50)
);
GO
INSERT INTO dbo.TestBatch (ID, Name)
VALUES (1, 'Thomas'), (2, 'Anna');
GO
SELECT * FROM dbo.TestBatch;
GO
- Each section of code between
GO
is treated as a batch
-
Execute All Batches at Once
- Click the Execute button or press F5
- SSMS will send each batch to SQL Server sequentially
GO
is not a T-SQL command; itβs a batch separator understood by SSMS and sqlcmd, but not SQL Server itself
- You cannot use
GO
inside stored procedures or functions
- All batches are executed in sequence, not in parallel
π§° Bonus Tip (Automated Batch Execution)
You can also execute a `.sql` script file containing multiple batches using the `sqlcmd` utility:
sqlcmd -S localhost -d AdventureWorks2022 -i C:\path\to\batch-script.sql
A batch is a group of one or more Transact-SQL (T-SQL) statements that are submitted together to SQL Server for execution. If there are no `GO` keywords in a set of statements, they are all considered to be in a single batch.
β
Advantages of Using Batches
If a syntax or compile-time error occurs in a batch, SQL Server may stop executing the remaining statements in that batch. This can be helpful during troubleshooting because it isolates the problematic code. However, runtime errors (such as divide-by-zero or constraint violations) may allow the batch to continue unless explicitly handled.
π Variables and Batches
Each batch is treated as a separate compilation unit. Therefore:
- Any variables (
DECLARE @var INT
, etc.) used in a batch must be declared within that batch.
- Variables do not carry over across batches unless passed via a stored procedure or function.
β οΈ When Not to Use Batching with Other Statements
The following `CREATE` statements must be executed as single-statement batches (i.e., no other SQL statements can appear in the same batch):
CREATE PROCEDURE
CREATE TRIGGER
CREATE VIEW
CREATE DEFAULT
CREATE RULE
This is because SQL Server requires these definitions to be compiled in isolation from other statements.
π§ How to Create a Batch: Using the `GO` Statement
The `GO` statement is not a T-SQL command, but rather a batch separator understood by SSMS, `sqlcmd`, and other tools. All statements between two `GO` commands form one batch. If no `GO` keyword is used, all statements in the query editor are submitted as one batch. Think of there being an implicit `GO` at the end of your submission.
π§ͺ Examples
Single Batch (No GO) : The following is treated as one batch:
UPDATE Employees
SET FirstName = 'Anthony',
LastName = 'Mann'
WHERE EmployeeID = 101;
SELECT *
FROM Employees
WHERE EmployeeID = 101;
Multiple Batches (Using GO):
USE Timesheets;
GO
UPDATE Employees
SET FirstName = 'Anthony',
LastName = 'Mann'
WHERE EmployeeID = 101;
SELECT *
FROM Employees
WHERE EmployeeID = 101;
In this example:
- The first
USE
statement is one batch.
- The
UPDATE
and SELECT
are part of the second batch.