Update Data In a MySQL Table Using MySQLi and PDO. The UPDATE statement is used to update existing records in a table. The MySQL UPDATE statement is used to update existing records in a table in a MySQL database. There are 3 syntaxes for the UPDATE statement depending on the type of update. ![]() SQL UPDATE Command Update command in SQL is used to change any record in the table. Records are to be manipulated or updated using update command. Conditional update is the most common type of update command used in MySQL also. You are requested to go through the command before using update command as both are to be used in proper combinations. Here is one simple command but before trying this please understand the implication of this. Without using any (or without using any restriction) the command will change all the records of the table. So let us start with the simple command. UPDATE student SET class='Five' This command will change all the records of the table student and will change all the class field to Five. This is not what is required in common cases so we will be changing records based on some conditions. Now we will change all the class four students to class five. Our command should selectively update those records for which class is equal to “four” and will update them to “five”. We will use one where clause along with update command for updating the records. UPDATE student SET class='Five' WHERE class='Four'. This command will update only those records for which class is equal to 'Four'. So this way we can update records selectively. Now let us move one more step and change the records selectively based on some value in some other field. We will change records for which class is equal to 'Four' and mark is more than 70. We will promote those students only who has got more than or equal to 70 mark. UPDATE student SET class='Five' WHERE class='Four' and mark >= 70 This will only change the records for which class=four and mark is more than or equal to 70. We have added two conditions by using AND as a logical operator. This way we can continue with adding more to the query. Depending on the logic requirement OR combination can be added to the WHERE clause to UPDATE the records. Updating multiple columns of a table We will use one more student table where we will store mark obtained by students in three subjects. You can download sql dump of this table at the end of this tutorial. Condition; In the UPDATE statement: • First, specify the table name that you want to update data after the UPDATE keyword. • Second, the SET clause specifies which column that you want to modify and the new values. To update multiple columns, you use a list comma-separated assignments. You supply the value in each column’s assignment in the form of a literal value, an expression, or a. • Third, specify which rows to be updated using a condition in the. The WHERE clause is optional. ![]()
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January 2019
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