Aliases are the temporary names given to table or column for the purpose of a particular SQL query. It is used when name of column or table is used other than their original names, but the modified name is only temporary.
- Aliases are created to make table or column names more readable.
- The renaming is just a temporary change and table name does not change in the original database.
- Aliases are useful when table or column names are big or not very readable.
- These are preferred when there are more than one table involved in a query.
- For column alias:
SELECT column as alias_name FROM table_name; column: fields in the table alias_name: temporary alias name to be used in replacement of original column name table_name: name of table
- For table alias:
SELECT column FROM table_name as alias_name; column: fields in the table table_name: name of table alias_name: temporary alias name to be used in replacement of original table name
Queries for illustrating column alias
- To fetch ROLL_NO from Student table using CODE as alias name.
SELECT ROLL_NO AS CODE FROM Student;
CODE 1 2 3 4
- To fetch Branch using Stream as alias name and Grade as CGPA from table Student_Details.
SELECT Branch AS Stream,Grade as CGPA FROM Student_Details;
Stream CGPA Information Technology O Computer Science E Computer Science O Mechanical Engineering A
Queries for illustrating table alias
- To fetch Grade and NAME of Student with Age = 20.
SELECT s.NAME, d.Grade FROM Student AS s, Student_Details AS d WHERE s.Age=20 AND s.ROLL_NO=d.ROLL_NO;
NAME Grade SUJIT O
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