![]() ![]() (To work around this, create a domain over the composite type, and apply the desired constraints as CHECK constraints of the domain.) Note however an important restriction of the current implementation: since no constraints are associated with a composite type, the constraints shown in the table definition do not apply to values of the composite type outside the table. Then the same inventory_item composite type shown above would come into being as a byproduct, and could be used just as above. Supplier_id integer REFERENCES suppliers, Whenever you create a table, a composite type is also automatically created, with the same name as the table, to represent the table's row type. SELECT price_extension(item, 10) FROM on_hand INSERT INTO on_hand VALUES (ROW('fuzzy dice', 42, 1.99), 1000) ĬREATE FUNCTION price_extension(inventory_item, integer) RETURNS numeric Having defined the types, we can use them to create tables: Note that the AS keyword is essential without it, the system will think a different kind of CREATE TYPE command is meant, and you will get odd syntax errors. ![]() The syntax is comparable to CREATE TABLE, except that only field names and types can be specified no constraints (such as NOT NULL) can presently be included. ![]() This provides the full power of the SQL query mechanism ( Chapter 7) for computing the rows to be inserted.Here are two simple examples of defining composite types: SELECT product_no, name, price FROM new_products INSERT INTO products (product_no, name, price) It is also possible to insert the result of a query (which might be no rows, one row, or many rows): INSERT INTO products (product_no, name, price) VALUES You can insert multiple rows in a single command: INSERT INTO products (product_no, name, price) VALUES (1, 'Cheese', DEFAULT) It fills the columns from the left with as many values as are given, and the rest will be defaulted.įor clarity, you can also request default values explicitly, for individual columns or for the entire row: The second form is a PostgreSQL extension. INSERT INTO products VALUES (1, 'Cheese') INSERT INTO products (product_no, name) VALUES (1, 'Cheese') In that case, the columns will be filled with their default values. If you don't have values for all the columns, you can omit some of them. Many users consider it good practice to always list the column names. INSERT INTO products (name, price, product_no) VALUES ('Cheese', 9.99, 1) INSERT INTO products (product_no, name, price) VALUES (1, 'Cheese', 9.99) For example, both of the following commands have the same effect as the one above: To avoid this you can also list the columns explicitly. The above syntax has the drawback that you need to know the order of the columns in the table. Usually, the data values will be literals (constants), but scalar expressions are also allowed. The data values are listed in the order in which the columns appear in the table, separated by commas. INSERT INTO products VALUES (1, 'Cheese', 9.99) For example, consider the products table from Chapter 5:Īn example command to insert a row would be: The command requires the table name and column values. To create a new row, use the INSERT command. Even if you know only some column values, a complete row must be created. You can also insert more than one row in a single command, but it is not possible to insert something that is not a complete row. The first thing to do before a database can be of much use is to insert data. When a table is created, it contains no data. ![]()
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