Placeholders and Bind Values
Some drivers support placeholders and bind
values. Placeholders, also called parameter
markers, are used to indicate values in a database statement that
will be supplied later, before the prepared statement is executed.
For example, an application might use the following to insert a row
of data into the sales table:
INSERT INTO sales (product_code, qty, price) VALUES (?, ?, ?)
or the following, to select the description for a product:
SELECT description FROM products WHERE product_code = ?
The ? characters are the placeholders. The
association of actual values with placeholders is known as
binding, and the values are referred to as
bind values.
When using placeholders with the SQL LIKE
qualifier, you must remember that the placeholder substitutes for the
whole string. So you should use "... LIKE ? ..." and include any wildcard characters in the value
that you bind to the placeholder.
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