Let's insert a new record that has been already existing in the table. If no matching data exists, the simple INSERT statement will be performed.If there's already a row, then it deletes matching data with the DELETE statement and uses a normal INSERT statement to insert a new row.It first tries to find out if there is any existing row in the table.On the other hand, if there is no row with the same key values, the new row is simply inserted into the table without any deletion.īy simply replacing the INSERT with REPLACE during the insertion of any row, MySQL will be performing the following operations: Essentially, if a row with identical key values already exists, it gets removed first, and the new row is inserted. ![]() In MySQL, the REPLACE statement is utilized to insert a fresh row into a table or to update an existing row with the same primary key or unique index. Since there was already an id 1, so it was updated with a new name and age. The ON DUPLICATE KEY UPDATE clause will update the name and age if it finds a record with the same id. You can use the ON DUPLICATE KEY UPDATE statement in your MySQL query when using PHPs mysqli or PDO libraries to. Alternatively, a new row will be inserted with the specified values if MySQL cannot find an already existing row with the same key.įor instance, in the above-created table students we'll try to insert a new row with an already existing id. PHP MYSQL UPDATE if Exist or INSERT if not. If any row with the duplicate key exists, the specified columns will be updated with the new values. The ON DUPLICATE KEY UPDATE clause is added at the end of the INSERT statement. It is commonly used if you want to update certain columns of an existing row or insert a new row with default values if the row doesn't already exist. It works by updating a row in a table if it already exists, or inserting a new row if it doesn't exist already. The syntax is basically the same as INSERT INTO, just replace INSERT by REPLACE. To apply MySQL INSERT if not exists, the ON DUPLICATE KEY UPDATE is also an alternative. Here's a cite from MySQL: REPLACE works exactly like INSERT, except that if an old row in the table has the same value as a new row for a PRIMARY KEY or a UNIQUE index, the old row is deleted before the new row is inserted. That way, if user_id of 5 exists already, it will be updated, otherwise, it will be inserted.Here, the insertion of the row with a duplicate key is ignored and the insertion of other rows will continue. For example, it might be something like (this is totally made-up of course): MAKE SURE A ROW IN cars WHERE user_id=5 IS SET WITH car_make='toyota', car_model='prius' And I feel like I need to do two similar (but different) statements to accomplish the same thing! What I need is some statement that will assure me that the data I want exists in the table, especially when I only want 1 row that satisfies my requirement. You could write a stored procedure to do this, or use a scripting language (bash, python, etc). The conditional syntax you tried is not supported. How can I make this into one elegant statement that works "atomically"? What happens if, in another process, the row is REMOVED between the SELECT and UPDATE statements? My UPDATE statement will fail where the INSERT statement should have run. If you don't add a unique index to the query column, then you can't do an upsert using only SQL. INSERT INTO cars (user_id, car_make, car_model) VALUES (5, 'toyota', 'prius') UPDATE cars SET car_make='toyota', car_model='prius' WHERE user_id=5 So, when I update this table, I always end up doing something like this (pseudo-code): result = SELECT * FROM cars WHERE user_id=5 If the user has no car, there is no entry in the table for that user. So let's say (this is just an arbitrary example), that I have a table that keeps track of a user's car, along with some info about the car. In MySQL, insert a new row only if data do not exist already by using the INSERT IGNORE statement or WHERE NOT EXISTS clause in the INSERT INTO statement. There are two possible consequences for each issued command when using a. ![]() And if 'John' does not exist, insert the full row with name+age+job. And if exists, I only want to update the age and job on that row. So if name is 'John', it should check if 'John' already exists. ![]() One approach is to use the REPLACE statement if you want to truly replace rows when the INSERT commands would fail due to duplicate UNIQUE or PRIMARY KEY values as described previously. ('name', Users.Name) I want to check, if name already exists in the 'name' column in the database. Very often, I want to run a query on one of my users where I want a row stored and associated with that user, in a 1-to-1 relationship. Use REPLACE INTO to Update the Record if It Exists Else Insert It in the MySQL Table.
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