# UPDATE Query in Oracle

ORACLE UPDATE
To update the existing records in a table, the Oracle UPDATE statement is used.

Syntax: To Update a table in simple steps.

UPDATE table_name
SET column_1 = expr_1,
column_2 = expr_2,
...
column_n = expr_n
WHERE conditions;


Syntax: To Update Table by selecting records from another table.

UPDATE table_name
SET column_1 = (SELECT expression
FROM source_table
WHERE conditions)
WHERE conditions;


Parameters:
table_name: It is used to specify the name of the table whose records need to be updated.
column_1, column_2, … column_n: It is used to specify the columns of the table whose values needs to be updated.
expression_1, expression_2, … expression_n: It is used to specify the values to be updated to the respective columns. For example, expression_1 will be inserted into column_1, expression_2 to column_2 and so on.
source_table: It is used to specify the table from which records will be selected and then will be updated to the desired table.
conditions: It is used to specify the conditions to be strictly satisfied in order to have a successful execution of the Update statement.

Example: Updating a single column of a table.
Students table before insertion:

 STUDENT_ID STUDENT_NAME STUDENT_AGE 1 Joy 5 2 Smiley 13 3 Happy 11

Query:

UPDATE students SET student_name = 'Jacob' WHERE student_id = 3;

Explanation:
The student_name will be updated as ‘Jacob’ where student_id is 3.
Students table after insertion:

 STUDENT_ID STUDENT_NAME STUDENT_AGE 1 Joy 5 2 Smiley 13 3 Jacob 11

Example: Updating multiple columns of a table.
Students table before insertion:

 STUDENT_ID STUDENT_NAME STUDENT_AGE 1 Joy 5 2 Smiley 13 3 Happy 11

Query:

UPDATE students SET student_name = 'Jacob', student_age = 15 WHERE student_id = 3;

Explanation:
The student_name will be updated as ‘Jacob’, and the student_age will be updated as 15 where student_id is 3.

Students table after insertion:

 STUDENT_ID STUDENT_NAME STUDENT_AGE 1 Joy 5 2 Smiley 13 3 Jacob 15

Example: Selecting records from another table.

UPDATE students SET student_name = (SELECT name FROM children WHERE children.name = students.student_name) WHERE age &lt; 15;

Explanation:
The ‘students’ table will be updated by retrieving the data from the ‘children’ table.