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You use update queries in Access databases to add, change, or delete the information in an existing record.You can think of update queries as a powerful form of the Find and Replace dialog box.In some cases, the conversion process might delete some data.For more information about restrictions when you convert data types, see the section Restrictions on data type conversions.the UPDATE statement is especially useful when you want to change many records or when the records that you want to change are in multiple tables. This is one of the most interesting questions I keep on getting on this email and I find that not everyone knows about it. Our requirement is that we have Table2 which has two rows where Col1 is 21 and 31.
Unlike the Find and Replace dialog box, an update query lets you: As a best practice when creating an update query, first create a select query that identifies the records that you want to update, and then convert that query to an update query that you can run to update the records.If the original value is in the form of a valid Internet Protocol (IP) address (four number triplets separated by a period: nnn.nnn) and the numbers happen to coincide with a Web address, the conversion results in a valid link.Otherwise, Access appends to the beginning of each value, and the resulting links are not valid.The dates that you can convert depend on the size of the number field.
Remember that Access stores all dates as serial dates, and it stores the date values as double-precision floating integers. Dates outside the range April 18, 1899 and September 11, 1900 exceed the size of a Byte field.
You cannot use an update query to add new records to a database, or to delete records from a database.