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An INSERT statement can also be used to retrieve data from other tables, modify it if necessary and insert it directly into the table. All this is done in a single SQL statement that does not involve any intermediary processing in the client application.
If your trigger is using the BEFORE option, the code within the trigger will be executed before the INSERT into the table occurs. A common use of the BEFORE trigger is to verify the input values of the INSERT, or modify the values accordingly. Now let's say we have a trigger that uses AFTER instead. The code within the trigger is executed after ...
Additionally there is a single-row version, UPDATE OR INSERT INTO tablename (columns) VALUES (values) [MATCHING (columns)], but the latter does not give you the option to take different actions on insert versus update (e.g. setting a new sequence value only for new rows, not for existing ones.)
Tables can be set to inherit their characteristics from a parent table. Data in child tables will appear to exist in the parent tables, unless data is selected from the parent table using the ONLY keyword, i.e. SELECT * FROM ONLY parent_table;. Adding a column in the parent table will cause that column to appear in the child table.
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price .
As the song goes, it's the most wonderful time of the year. The holidays are expected to be a joyful, harmonious, and celebratory time of year… but for many, it can also bring a mix of emotional ...
The U.S. believes Chinese intelligence hacked into AT&T, Verizon and Lumen Technologies and gained significant access, including records of phone calls and text messages for many people ...
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...