............................................................................ 430 9.82. Transaction ID and Snapshot Information Functions ...................................................... 430 9.83 ................................................................. 431 9.84. Deprecated Transaction ID and Snapshot Information Functions ....................................... 432 9.85. Committed Transaction Checking Functions ............................................................ 429 9.27.8. Transaction ID and Snapshot Information Functions .................................... 430 9.27.9. Committed Transaction

Functions ......................................................................... 405 9.82. Transaction ID and Snapshot Information Functions ................................................. 406 xxiv PostgreSQL ................................................................. 407 9.84. Deprecated Transaction ID and Snapshot Information Functions ................................. 407 9.85. Committed Transaction Validity Checking Functions ...................................................... 405 9.27.8. Transaction ID and Snapshot Information Functions ............................... 406 9.27.9. Committed Transaction

............................................................................ 411 9.80. Transaction ID and Snapshot Information Functions ...................................................... 412 9.81 ................................................................. 413 9.82. Deprecated Transaction ID and Snapshot Information Functions ....................................... 413 9.83. Committed Transaction Checking Functions ............................................................ 411 9.26.8. Transaction ID and Snapshot Information Functions .................................... 412 9.26.9. Committed Transaction

Functions ......................................................................... 388 9.80. Transaction ID and Snapshot Information Functions ................................................. 389 9.81. Snapshot ................................................................. 390 9.82. Deprecated Transaction ID and Snapshot Information Functions ................................. 391 xxiv PostgreSQL 16.1 Documentation Validity Checking Functions ...................................................... 388 9.26.8. Transaction ID and Snapshot Information Functions ............................... 389 9.26.9. Committed Transaction

............................................................................ 398 9.76. Transaction ID and Snapshot Information Functions ...................................................... 399 9.77 ................................................................. 399 9.78. Deprecated Transaction ID and Snapshot Information Functions ....................................... 400 9.79. Committed Transaction constraint in the orders table that references the products table: CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products (product_no), quantity integer

Functions ........................................................................... 377 9.76. Transaction ID and Snapshot Information Functions ................................................. 377 9.77. Snapshot ................................................................. 378 9.78. Deprecated Transaction ID and Snapshot Information Functions ................................. 378 9.79. Committed Transaction constraint in the orders table that references the products table: CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products (product_no), quantity integer

............................................................................ 404 9.78. Transaction ID and Snapshot Information Functions ...................................................... 404 9.79 ................................................................. 405 9.80. Deprecated Transaction ID and Snapshot Information Functions ....................................... 405 9.81. Committed Transaction constraint in the orders table that references the products table: CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products (product_no), quantity integer

Functions ........................................................................... 383 9.78. Transaction ID and Snapshot Information Functions ................................................. 383 9.79. Snapshot ................................................................. 384 9.80. Deprecated Transaction ID and Snapshot Information Functions ................................. 385 9.81. Committed Transaction constraint in the orders table that references the products table: CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products (product_no), quantity integer

............................................................................ 386 9.74. Transaction ID and Snapshot Information Functions ...................................................... 386 xxv ................................................................. 387 9.76. Deprecated Transaction ID and Snapshot Information Functions ....................................... 387 9.77. Committed Transaction constraint in the orders table that references the products table: CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products (product_no), quantity integer

constraint in the orders table that references the products table: CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products (product_no), quantity integer You can also shorten the above command to: 64 Data Definition CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products, quantity integer ); because in TABLE tree ( node_id integer PRIMARY KEY, parent_id integer REFERENCES tree, name text, ... ); A top-level node would have NULL parent_id, but non-NULL parent_id entries would be con-