![]() See Section 13.2.7.3, “INSERT DELAYED Statement”, UPDATE to refer to the row to be inserted. In MySQL 8.0.19 and later, a row alias with one or more optionalĬolumn aliases can be used with ON DUPLICATE KEY Updated if a row to be inserted would cause a duplicate value in a ![]() In MySQL 8.0.19 and later to insert rows from a single table.ĭUPLICATE KEY UPDATE clause enables existing rows to be SELECT form inserts rows selected from another table | col_alias assignment_list:įorms of the statement insert rows based on explicitly specified ![]() ![]() ON DUPLICATE KEY UPDATE Statement 13.2.7.3 INSERT DELAYED Statement INSERT When this runs, the first 3 rows are new and get inserted but the last row gets updated.13.2.7.1 INSERT. INSERT INTO users (listid,email,age,name) VALUES DUPLICATE KEY UPDATE listid=VALUES(listid), ON DUPLICATE KEY UPDATE val1=1, val2=2, val3=3, val4=4 INSERT INTO users (val1, val2, val3, val4) VALUES (1, 2, 3, 4) syntax to insert on duplicate update with one row Now our database table is ready to batch insert ON DUPLICATE KEY UPDATE. or create table with composite primary key from the start drop the old primary key if it exists: ALTER TABLE users DROP PRIMARY KEY ĪLTER TABLE users ADD PRIMARY KEY (email, listid) So, we either alter the table above and add a composite primary key or define it from the start: We need a unique key, and MySQL allows us to specify multiple columns via a composite key, which uniquely indentifies an entity occurrence. Now, when using INSERT on DUPLICATE KEY UPDATE, we need to specify the criteria that the database needs to check in order to decide if it should update or insert. Insert into users (listid,email,age,name) values that John, the same user, is inserted twice but we want to allow that as John belongs to a different list or listid. Let’s start with a simple mysql users table and insert some initial data with a multiple insert into statement. So, email by itself is not the only unique criteria for a user but the unique criteria is based on multiple columns. So, INSERT on DUPLICATE KEY UPDATE is most likely the optimal query but how do you do that for multiple rows? And, how do you do that based on multiple criteria for uniqueness? Maybe I want to allow the same emails in the table as they belong to a different list or a different user which are different columns in the table. But, it should probably be avoided as it actually performs a DELETE and INSERT operation and updates all indexes. REPLACE INTO seems like a great solution considering that the query has the same syntax as a normal INSERT INTO. This leaves you with a choice of using REPLACE INTO or INSERT on DUPLICATE KEY UPDATE. You want to offload such logic to the database and do it all with 1 query. It would not be optimal to write a loop and for each row, check if email exists (assuming this is the unique criteria for a user), and then insert or update. This is a very common scenario where you need to figure out if you should update or insert. Now you need to insert 10 more rows of data but you don’t know if the 10 new rows are for new users or if they are attributes for users you already have in the database. You have a table with some data, lets say it is user information with emails, names, ages, etc.
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