PHP Tutorials
- What is MySqli
- mysql query
- mysql query example
- InnoDB
- mysql column Type
- CRUD Example
- Connection Using Function
- mysql keys
- SELECT
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- Count no of Rows
- ALIAS
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- BETWEEN
- COMPARISON OPERATOR
- DELETE
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- DISTINCT
- EXISTS
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- HAVING
- IN
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- IS NULL & IS NOT NULL
- LIKE
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- SELECT LIMIT
- SUBQUERY
- TRUNCATE
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- Concat & Group_Concat
- mysql Function
- Mysql Insert Id
- MySql Aggregate Function
- Mysql Join
- JOIN in MySql
- Trigger
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- SQL Injection
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- Interview Questions
Important Link
is NULL
A field with a NULL value is a field with no value.
Note: A NULL value is different from a zero value or a field that contains spaces. A field with a NULL value is one that has been left blank during record creation!
IS NULL and IS NOT NULL operators is used to check null or not.
The IS NULL Operator
The IS NULL operator is used to test for empty values (NULL values).
File Name :
SELECT emp_name, contact_no, address
FROM Employee WHERE contact_no IS NULL;
SELECT emp_name, contact_no, address
FROM Employee WHERE contact_no IS NULL OR contact_no='';
SELECT * FROM ittutorial WHERE (id IN ('value1', 'value2', 'value3') OR id IS NULL)
IS NOT NULL Operator
The IS NOT NULL operator is used to test for non-empty values (NOT NULL values).
File Name :
SELECT emp_name, contact_no, address FROM Employee WHERE contact_no IS NOT NULL;
SELECT ID, NAME, ADDRESS, SALARY
FROM CUSTOMERS WHERE SALARY IS NOT NULL;
SELECT ID, NAME, ADDRESS, SALARY
FROM CUSTOMERS WHERE SALARY IS NOT NULL OR salary !='' ;
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