What Happens If Unique Value Constraints Are Violated

Q

What Happens If Unique Value Constraints Are Violated? - MySQL FAQs - Understanding SQL INSERT, UPDATE and DELETE Statements

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A

If you are inserting a new record that has values violating a unique constraint, you will get an error. Note that primary key column has a unique value constraint by default. The following tutorial exercise gives you some good examples:

mysql> INSERT INTO fyi_links (url) VALUES ('www.other.com');
ERROR 1062 (23000): Duplicate entry '0' for key 1

mysql> INSERT INTO fyi_links VALUES (101, 
  'sql.fyicenter.com', 
  NULL,
  0,
  '2006-04-30');
ERROR 1062 (23000): Duplicate entry '101' for key 1

2007-05-11, 5372👍, 0💬

What Happens If Unique Value Constraints Are Violated
What Happens If Unique Value Constraints Are Violated? - MySQL FAQs - Understanding SQL INSERT, UPDATE and DELETE Statements If you are inserting a new record that has values violating a unique constraint, you will get an error. Note that primary key column has a unique value constraint by default. ... 2007-05-11, 5373👍, 0💬

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How To Update Values in a Table
How To Update Values in a Table? - MySQL FAQs - Understanding SQL INSERT, UPDATE and DELETE Statements If you want to update some values in one row or multiple rows in a table, you can use the UPDATE statement. The tutorial script below shows a good example: mysql> UPDATE fyi_links SET counts = 999,... 2007-05-11, 5140👍, 0💬

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How To Insert a New Row into a Table? - MySQL FAQs - Understanding SQL INSERT, UPDATE and DELETE Statements To insert a new row into a table, you should use the INSERT INTO statement with values specified for all columns as shown in the following example: mysql> INSERT INTO fyi_links VALUES (101, 'd... 2007-05-11, 5092👍, 0💬

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