The sub-query must yield no more than one row when executed.
To do this in SQL, we specify that we want to change the structure of the table using the ALTER TABLE command, followed by a command that tells the relational database that we want to rename the column.
The UPDATE statement updates data in existing columns; it does not create new columns.
To add new columns, see Altering Columns and Creating New Columns.
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The first syntactical form, called a searched update, updates the value of one or more columns for all rows of the table for which the WHERE clause evaluates to TRUE.