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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →DDL defines or changes database objects; DML retrieves or changes the data stored in them. For example, CREATE TABLE defines a table, while INSERT, SELECT, UPDATE and DELETE work with its rows. The distinction is about what a statement acts on—not whether a particular database automatically commits it or allows it to be rolled back.
What DDL and DML mean
DDL stands for Data Definition Language. It describes SQL statements used to define or alter database structures and objects, such as tables. Microsoft’s SQL Server statement list includes CREATE, ALTER, DROP, RENAME and TRUNCATE TABLE in its DDL category. Microsoft’s Transact-SQL statement reference
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DML stands for Data Manipulation Language. It covers statements used to retrieve or work with data in database objects. Microsoft lists INSERT, UPDATE, DELETE, SELECT, MERGE and BULK INSERT as SQL Server DML statements. Microsoft’s SQL Server queries documentation
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DDL vs. DML at a glance
| Category | What it affects | Typical purpose | Examples |
|---|---|---|---|
| DDL | Database structure and objects | Create, change, rename or remove objects | CREATE, ALTER, DROP, TRUNCATE TABLE |
| DML | Data stored in database objects | Retrieve, add, change or remove data | SELECT, INSERT, UPDATE, DELETE |
A useful shorthand is: DDL changes the shape of the database; DML queries or changes its contents. The table lists examples documented for SQL Server; statement syntax and support can differ among database products.
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Examples: defining a table and working with its rows
This illustrative sequence first creates a table, then inserts, retrieves and updates a row:
CREATE TABLE customers (
customer_id INTEGER,
name VARCHAR(100)
);
INSERT INTO customers (customer_id, name)
VALUES (1, 'Ari');
SELECT customer_id, name FROM customers;
UPDATE customers
SET name = 'Ari Lee'
WHERE customer_id = 1;CREATE TABLE defines the database object, so it is DDL. The other statements operate on the table’s data, so they are DML. This example is for illustration: supported data types, constraints and exact syntax depend on the database system.
Common DDL statements
CREATE TABLEcreates a table and defines its columns.ALTER TABLEchanges a table’s structure.DROP TABLEremoves the table object.TRUNCATE TABLEis categorized as DDL in Microsoft’s SQL Server statement list; check your database’s documentation for its precise behavior.
Common DML statements
SELECTretrieves data.INSERTadds rows.UPDATEchanges values in rows.DELETEremoves rows.MERGEandBULK INSERTare also included in Microsoft’s SQL Server DML list.
Is SELECT DML or DQL?
In the SQL Server documentation and Oracle’s statement reference cited here, SELECT is classified as DML. Oracle describes it as a limited form of DML because it accesses data without changing it. Oracle Database 18 SQL Language Reference: Types of SQL Statements
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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Some courses and learning materials put querying in a separate category called DQL (Data Query Language). That is a teaching convention readers may encounter; it does not change what SELECT does. These vendor references establish how SQL Server and Oracle classify the statement, not one taxonomy used universally by every database or course.
DDL and DML do not determine transaction behavior
DDL and DML describe the kind of work a statement performs. They do not, by themselves, tell you whether a specific database will commit the statement automatically, let you roll it back, or require particular locks.
For example, Oracle Database 19c documentation says DML statements do not implicitly commit the current transaction. That is an Oracle-specific statement, not a rule to apply to every product. Oracle Database 19c Database Concepts: Transactions DDL transaction handling varies among database products and versions, so consult the documentation for the system you use before relying on commit or rollback behavior.
Locking can also depend on the database. Oracle Database 18 documentation says its CREATE, ALTER and DROP commands require exclusive access to the specified object; an open transaction on a table is one example of a condition that can cause ALTER TABLE to fail. This describes Oracle’s documented behavior, not a universal locking rule. Oracle Database 18 SQL Language Reference: Types of SQL Statements
How to handle schema-changing statements safely
DDL can alter or remove objects, so verify the statement and its target before executing it. Microsoft Support specifically warns that Access data-definition queries can alter or delete database objects without confirmation dialogs and advises making a backup copy of the tables involved. Microsoft Support: Create or modify tables or indexes by using a data-definition query
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- Check the database and object named in the statement, especially before using
DROPor another destructive operation. - Use a safe test environment when appropriate, rather than experimenting on important production objects.
- Back up important data before consequential schema edits, following guidance appropriate to your database platform.
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