原文链接：https://www.f2er.com/postgresql/195560.htmlWITH test(x) AS ( VALUES (''),('.'),('.0'),('0.'),('0'),('1'),('123'),('123.456'),('abc'),('1..2'),('1.2.3.4'),('1x234'),('1.234e-5'))
SELECT x,x ~ '^([0-9]+[.]?[0-9]*|[.][0-9]+)$' AS isnumeric FROM test;
WITH test(x) AS ( VALUES (''),('1.2.3.4')) SELECT x,x ~ '^[0-9]*.?[0-9]*$' AS isnumeric FROM test;------下面才是正解
