How to use foreach in MySQL to update data in bulk?

2 years ago
Olivia Parker
2 minutes

In MySQL, batch data updates can be performed using the FOREACH statement.

Here are the general steps for batch updating data using the FOREACH statement:

  1. Firstly, create a temporary table to store the data that needs to be updated. The structure of the temporary table should be the same as the table being updated.
  2. Establish a temporary table named temp_table with columns id and name of specified data types.
  3. Next, the data to be updated is inserted into a temporary table. One option is to use the INSERT INTO statement to copy data from the source table to the temporary table.
  4. The data from the source table that meets the specified condition is being inserted into a temporary table with the corresponding id and name columns.
  5. Next, use a FOREACH statement to iterate through each row of the temporary table and perform the update operation. You can use the UPDATE statement to update the data.
  6. Initialize a variable called done as an integer with a default value of false, and declare variables temp_id as an integer and temp_name as a VARCHAR with a length of 255. Create a cursor named cur for selecting id, name, etc. from the temp_table. Set a handler to set done to true if no more rows are found. Open the cursor and loop through fetching the values into temp_id, temp_name, etc. If done is true, leave the loop. Update the target_table with the values fetched from temp_table where the id matches. Close the cursor when finished.
  7. Finally, drop the temporary table.
  8. Remove the temporary table named temp_table.

The above are the general steps for updating data in bulk using the FOREACH statement. Please make necessary adjustments based on actual needs.

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