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An example use-case is "CHECK(num_nonnulls(a,b,c) = 1)" to assert that exactly one of a,b,c isn't NULL. The functions are variadic, so they can also be pressed into service to count the number of null or nonnull elements in an array. Marko Tiikkaja, reviewed by Pavel Stehule
32 lines
1.1 KiB
SQL
32 lines
1.1 KiB
SQL
--
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-- num_nulls()
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--
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SELECT num_nonnulls(NULL);
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SELECT num_nonnulls('1');
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SELECT num_nonnulls(NULL::text);
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SELECT num_nonnulls(NULL::text, NULL::int);
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SELECT num_nonnulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL);
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SELECT num_nonnulls(VARIADIC '{1,2,NULL,3}'::int[]);
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SELECT num_nonnulls(VARIADIC '{"1","2","3","4"}'::text[]);
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SELECT num_nonnulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i));
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SELECT num_nulls(NULL);
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SELECT num_nulls('1');
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SELECT num_nulls(NULL::text);
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SELECT num_nulls(NULL::text, NULL::int);
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SELECT num_nulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL);
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SELECT num_nulls(VARIADIC '{1,2,NULL,3}'::int[]);
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SELECT num_nulls(VARIADIC '{"1","2","3","4"}'::text[]);
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SELECT num_nulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i));
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-- special cases
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SELECT num_nonnulls(VARIADIC NULL::text[]);
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SELECT num_nonnulls(VARIADIC '{}'::int[]);
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SELECT num_nulls(VARIADIC NULL::text[]);
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SELECT num_nulls(VARIADIC '{}'::int[]);
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-- should fail, one or more arguments is required
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SELECT num_nonnulls();
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SELECT num_nulls();
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