Get Started: SQL Comments

In This Article, You Will Know About SQL Comments. 

SQL Comments – Before moving ahead, let’s know a bit about the SQL CASE Statement.

Table of Contents

SQL Comments

In SQL Comments are used to represent the statement that will not be executed. It is like an explanation statement to define why an SQL query is written.

Single-Line Comments

Single line comments start with .

If any SQL statement starts with sign then it will be ignored by SQL to execute.

Example: Use the single-line comment to define a SQL query.

				
					-- Select all columns from the table Data_1

SELECT * FROM Data_1; 

				
			

Example: Use the single-line comment to define a SQL query.

				
					SELECT * FROM Data_1   -- Where Name = 'Alex';
				
			

Example: Use the single-line comment to prevent executing a SQL query.

				
					SELECT * FROM Data_1
Where Name = 'Alex' -- Where Name = 'Rolex';
				
			

Multi-line Comments

Multi-line comments start with /* and end with */.

Any text between /* and */ will be ignored.

If any SQL statement between /* and */ sign will be ignored by SQL to execute.

Example: Use the Multi-line comment to define a SQL query.

				
					/* Select all columns 
from the table Data_1 */

SELECT * FROM Data_1; 
				
			

Example: Use the Multi-line comment to define a SQL query.

				
					/* Select columns 
Name, Roll_No, and Section_ID
from the table Data_1 */

SELECT * FROM Data_1; 

				
			

Example: Use the Multi-line comment to ignore statements between a SQL query.

				
					SELECT * FROM Data_1
Where Name = 'Alex', /* Roll_No = 8 */, Section_ID = 'A';
				
			

Example: Use the Multi-line comment to ignore a part of a SQL query.

				
					SELECT * FROM Data_1
WHERE Name LIKE 'A%'
OR Name LIKE 'R%'
/* OR Name LIKE 'S%' /*
OR Name LIKE 'K%'
ORDER BY Section_ID;
				
			

If you find anything incorrect in the above-discussed topic and have further questions, please comment below.

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