PostgreSQL/Data Type/Boolean

Содержание

1 boolean value "t"
2 Checking Boolean values: yes
3 Checking for "false" Boolean values
4 Compare the value of a boolean field against any of the values
5 Implying Boolean "true"
6 NOT for boolean value
7 NULL will not register as either true or false
8 The difference between true and "true"
9 Using the boolean type

boolean value "t"

postgres=#
postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# select * from myTable;
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0451198492 | f
 0394900014 | f
 0441172717 | t
 0451160916 |
(7 rows)
postgres=#
postgres=# SELECT * FROM myTable WHERE in_stock != "t";
    isbn    | in_stock
------------+----------
 0451198492 | f
 0394900014 | f
(2 rows)
postgres=#
postgres=# drop table myTable;
DROP TABLE
postgres=#

Checking Boolean values: yes

postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# -- Checking Boolean values
postgres=#
postgres=# SELECT * FROM myTable WHERE in_stock = "yes";
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0441172717 | t
(4 rows)
postgres=#
postgres=#
postgres=# drop table myTable;
DROP TABLE
postgres=#
postgres=#

Checking for "false" Boolean values

postgres=#
postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# select * from myTable;
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0451198492 | f
 0394900014 | f
 0441172717 | t
 0451160916 |
(7 rows)
postgres=#
postgres=# -- Checking for "false" Boolean values
postgres=#
postgres=# SELECT * FROM myTable WHERE in_stock = "no";
    isbn    | in_stock
------------+----------
 0451198492 | f
 0394900014 | f
(2 rows)
postgres=#
postgres=#
postgres=#
postgres=# drop table myTable;
DROP TABLE
postgres=#
postgres=#

Compare the value of a boolean field against any of the values

postgres=#
postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# select * from myTable;
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0451198492 | f
 0394900014 | f
 0441172717 | t
 0451160916 |
(7 rows)
postgres=#
postgres=# -- Compare the value of a boolean field against any of the values
postgres=#
postgres=# SELECT * FROM myTable WHERE NOT in_stock;
    isbn    | in_stock
------------+----------
 0451198492 | f
 0394900014 | f
(2 rows)
postgres=#
postgres=# drop table myTable;
DROP TABLE
postgres=#

Implying Boolean "true"

postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# -- Implying Boolean "true"
postgres=#
postgres=# SELECT * FROM myTable WHERE in_stock;
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0441172717 | t
(4 rows)
postgres=#
postgres=# drop table myTable;
DROP TABLE
postgres=#

NOT for boolean value

postgres=#
postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# select * from myTable;
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0451198492 | f
 0394900014 | f
 0441172717 | t
 0451160916 |
(7 rows)
postgres=#
postgres=#
postgres=# SELECT * FROM myTable WHERE NOT in_stock;
    isbn    | in_stock
------------+----------
 0451198492 | f
 0394900014 | f
(2 rows)
postgres=#
postgres=#
postgres=#
postgres=# drop table myTable;
DROP TABLE

NULL will not register as either true or false

postgres=#
postgres=#
postgres=# CREATE TABLE myTable (isbn text, in_stock boolean);
CREATE TABLE
postgres=#
postgres=# INSERT INTO myTable VALUES ("0385121679", true);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("039480001X", "t");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("044100590X", "true");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451198492", false);
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0394900014", "0");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0441172717", "1");
INSERT 0 1
postgres=# INSERT INTO myTable VALUES ("0451160916");
INSERT 0 1
postgres=#
postgres=# select * from myTable;
    isbn    | in_stock
------------+----------
 0385121679 | t
 039480001X | t
 044100590X | t
 0451198492 | f
 0394900014 | f
 0441172717 | t
 0451160916 |
(7 rows)
postgres=#
postgres=# -- NULL will not register as either true or false
postgres=#
postgres=# SELECT * FROM myTable WHERE in_stock IS NULL;
    isbn    | in_stock
------------+----------
 0451160916 |
(1 row)
postgres=#
postgres=#
postgres=# drop table myTable;
DROP TABLE
postgres=#

The difference between true and "true"

postgres=#
postgres=# -- The difference between true and "true"
postgres=#
postgres=# SELECT true AS boolean_t,
postgres-#      "true" AS string_t,
postgres-#       false AS boolean_f,
postgres-#      "false" AS string_f;
 boolean_t | string_t | boolean_f | string_f
-----------+----------+-----------+----------
 t         | true     | f         | false
(1 row)
postgres=#

Using the boolean type

postgres=#
postgres=#
postgres=# -- Using the boolean type
postgres=#
postgres=# CREATE TABLE test1 (a boolean, b text);
CREATE TABLE
postgres=# INSERT INTO test1 VALUES (TRUE, "sic est");
INSERT 0 1
postgres=# INSERT INTO test1 VALUES (FALSE, "non est");
INSERT 0 1
postgres=#
postgres=# SELECT * FROM test1;
 a |    b
---+---------
 t | sic est
 f | non est
(2 rows)
postgres=#
postgres=# SELECT * FROM test1 WHERE a;
 a |    b
---+---------
 t | sic est
(1 row)
postgres=#
postgres=# drop table test1;
DROP TABLE
postgres=#

PostgreSQL/Data Type/Boolean

Содержание

boolean value "t"

Checking Boolean values: yes

Checking for "false" Boolean values

Compare the value of a boolean field against any of the values

Implying Boolean "true"

NOT for boolean value

NULL will not register as either true or false

The difference between true and "true"

Using the boolean type

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