MySQL SELECT语句的“长度”字段大于1

Question

I have an LINK field in my table. Some rows have a link, some don't.

I'd like to select all rows where LINK is present. (length is greater than X characters).

How do I write this?

Answer 1

How about:

SELECT * FROM sometable WHERE CHAR_LENGTH(LINK) > 1

Here's the MySql string functions page (5.0).

Note that I chose CHAR_LENGTH instead of LENGTH , as if there are multibyte characters in the data you're probably really interested in how many characters there are, not how many bytes of storage they take. So for the above, a row where LINK is a single two-byte character wouldn't be returned - whereas it would when using LENGTH .

Note that if LINK is NULL , the result of CHAR_LENGTH(LINK) will be NULL as well, so the row won't match.

Answer 2

select * from [tbl] where [link] is not null and len([link]) > 1

对于MySQL用户：

LENGTH([link]) > 1

Answer 3

Just in case anybody want to find how in oracle and came here (like me), the syntax is

select length(FIELD) from TABLE

just in case ;)

Answer 4

Try:

SELECT
    *
FROM
    YourTable
WHERE
    CHAR_LENGTH(Link) > x