SQL 仅当字符串以数值开头时才选择字符串的数字部分
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Select only numeric part of string only if it starts with a numeric value
提问by Phill Pafford
This is only giving me the last character (numeric) but I need the whole numeric string
这只是给我最后一个字符（数字），但我需要整个数字字符串
SELECT substring('123 Main Street' FROM '%#"[0-9]#"%' FOR '#')
- Results: 3
- Expecting: 123
- 结果：3
- 预期：123
This gives me the same results but I need it to return a blank value:
这给了我相同的结果，但我需要它返回一个空白值：
SELECT substring('Main 123 Street' FROM '%#"[0-9]#"%' FOR '#')
- Results: 3
- Expecting:
- 结果：3
- 期待：
NOTE: Postgres 7.4
注意：Postgres 7.4
Helpful Link: http://www.postgresql.org/docs/7.4/static/functions-matching.html
有用的链接：http: //www.postgresql.org/docs/7.4/static/functions-matching.html
UPDATE:
更新：
SELECT substring('Main 123 Street' FROM '[0-9]+')
SELECT substring('123 Main Street' FROM '[0-9]+')
- Both now return: 123
- Still need to skip or return full string of: 'Main 123 Street'
- 现在两者都返回：123
- 仍然需要跳过或返回完整字符串：'Main 123 Street'
UPDATE 2:
更新 2：
Almost have it:
差不多了：
This gives me the results I want if it doesn't start with a numeric value:
如果它不以数值开头，这会给我我想要的结果：
SELECT
COALESCE(substring('Main 123 Street' FROM '[0-9]*') || 'Main 123 Street', ''),
substring('Main 123 Street' FROM '[0-9]*')
But this gives me both and I only want the second condition:
但这给了我两个，我只想要第二个条件：
SELECT
COALESCE(substring('123 Main Street' FROM '[0-9]*') || '123 Main Street', ''),
substring('123 Main Street' FROM '[0-9]*')
I GOT IT!!! Thanks for all who posted:
我知道了！！！感谢所有发帖的人：
SELECT CASE
WHEN COALESCE(substring(db_column FROM '[0-9]*'), db_column) != '' THEN COALESCE(substring(db_column FROM '[0-9]*'), db_column)
ELSE db_column
END AS addsress_string
FROM db_table
采纳答案by Justin Morgan
I don't know postgresql regex syntax, but in most regex you would write [0-9]+. Without the quantifier, [0-9]matches a single character.
我不知道 postgresql 正则表达式的语法，但在大多数正则表达式中你会写[0-9]+. 没有量词，[0-9]匹配单个字符。
回答by rmmh
I don't have a Postgres install to test with, but something like this might work:
我没有要测试的 Postgres 安装，但这样的事情可能会奏效：
SELECT substring('123 Main Street' FROM '^[0-9]+')
SELECT substring('123 Main Street' FROM '^[0-9]+')
That returns nothing if it doesn't start with a number. If you want to return the full string instead, this should work:
如果它不以数字开头，则不返回任何内容。如果你想返回完整的字符串，这应该有效：
SELECT substring('123 Main Street' FROM '^[0-9]+|.*')
SELECT substring('123 Main Street' FROM '^[0-9]+|.*')
回答by Allan Registos
Maybe it is not yet too late to improve on rmmh's answer.
也许现在改进 rmmh 的答案还为时不晚。
This works for me:
这对我有用：
SELECT substring(column_name FROM '[0-9]+') FROM TableName;
In postgresql, just remove the caret for the numbers to show.
在 postgresql 中，只需删除要显示的数字的插入符号。
if column_name = 'XXXX-0001'the result will be:
如果column_name = 'XXXX-0001'结果是：
0001
