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So we could think in terms of creating a re-usable module which would implement that logic.This is the intention of UPDATE staff SET salary = 1200 WHERE name = ' Bob'; UPDATE staff SET salary = 1200 WHERE name = ' Jane'; UPDATE staff SET salary = 1200 WHERE name = ' Frank'; UPDATE staff SET salary = 1200 WHERE name = ' Susan'; UPDATE staff SET salary = 1200 WHERE name = ' John'; “key_columns” specifies the columns which will be used to identify rows which need to be updated (using WHERE). The first element provides the value of the column (specified by “key_columns”) to identify the row to be updated.We can easily contrive for an “updates” table to exist by creating a temporary table and populating it.It is relatively straightforward to populate a table with multiple rows with just one query (or at least, far fewer queries than the number of rows desired).
A more effective solution to this problem is to attempt to reduce the number of UPDATE statements.
Similarly, let’s say we want to update two fields, salary and bonus.
If we want to update more than one column, whereas previously we specified the new value using a scalar, when there is more than one column to update, we use an Array Ref.
A requirement arises in many systems to update multiple SQL database rows.
For small numbers of rows requiring updates, it can be adequate to use an UPDATE statement for each row that requires an update.
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(It will use placeholders and parameter binding if it thinks it’s appropriate.) If given our second example with two distinct values, will spot that there are two distinct values, 12, and will effect this with two UPDATE statements as described above.