We can avoid unnecessary read operations on databases by using the UPSERT operation for updating the records.If we use the PostgreSQL UPSERT feature, then for each update, we actually remove an additional read from the table.The PostgreSQL UPSERT is nothing but more than two data manipulation operation combined together as an Update operation and an Insert operation.We can use the UPDATE clause as the action of the INSERT INTO statement as defined below: Now, if we want to concatenate the new company email with the old one while inserting a company table that already exists. The following statement is similar to the above statement, but it will use the comp_name column of the company table instead of the unique constraint comp_name as the target of the INSERT statement. The above statement defines that if the company name exists in the company table, do nothing and just ignore the same. INSERT INTO CONFLICT ON CONSTRAINT company_comp_name_key Consider an example where Facebook has changed its email id from to will use the following INSERT ON CONFLICT statement for demonstrating the UPSERT feature: Now we can update that the email id information of any row using an UPDATE statement. Illustrate the result of the above INSERT statement by using the following snapshot and the SELECT statement: INSERT INTO company (comp_name, comp_email) Now we will insert some records into the table by INSERT INTO statement as follows: In addition, we added the UNIQUE constraint on the comp_name column of the company table to ensure the company’s uniqueness. Here you can see that the table company contains four columns as comp_id, comp_name, comp_email, and comp_contact. We will create a company table by using the following CREATE TABLE statement. Let’s create a table named ‘company’ in order to understand the PostgreSQL UPSERT feature: In order to check whether a record already exists in the table, the PostgreSQL UPSERT statement uses the record’s unique identifier as the key to match records in the table.Įxamples to Implement UPSERT in PostgreSQL.But in the case of the INSERT operation, the UPSERT and IF EXISTS operations use the same number of reading operations on the table. If we compare the IF EXISTS and UPSERT in order to understand the working of the UPSERT, then the for each update operation, the UPSERT removes an additional read from the table.The UPSERT combines two DML’s first is an UPDATE, and the second is an INSERT.DO UPDATE SET column_name_1 = value_field_1, … WHERE predicate : Defines we can update some fields in the table.Action: DO NOTHING: Defines that if a table already contains the do nothing.WHERE condition: Defines the WHERE clause with a condition.ON CONSTRAINT constraint_name: Defines the name of constraint name can be the UNIQUE constraint.In order to support the UPSERT operation, PostgreSQL added the ON CONFLICT target action. The following command will set a new price 19.49 if the price of any of the books in the table is 25.00.įollowing PHP script (say enter-bookid.php) will update the existing data in our book table.INSERT INTO table(columns) VALUES(values) This is not the only format to update a table, but in all cases, you have to use SET keyword and supply the new value to an existing value of a column or a number of columns.įollowing is the structure of the table whose data will be updated.Ĭode: UPDATE book SET price = 19.49 WHERE price = 25.00 Where table_name is the associated table, column1, 2, 3 are column names and new_value 1, 2, 3 are values to be modified to, some_column_name is a column name of the associated table and existing_value is the value present in the some_column_name column. UPDATE command is used to modify existing data of a table.įollowing is the usage of PostgreSQL UPDATE command to modify data of a PostgreSQL table.Ĭode: UPDATE table_name SET column_name1 = new_value1, column_name2 = new_value2, column_name3 = new_value3 WHERE some_column_name = existing_value We have also covered how to do the same using PHP-PostgreSQL. ![]() This document discusses how to update data of a table using PostgreSQL UPDATE command.
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