SQL 选择列以 \ 开头的位置
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SQL select where column begins with \
提问by Korhan Ozturk
I'm trying to find all the data in ColumnXwhere the Data begins with a \.
Is like '\%'what I'm looking for? But the \has to be at the beginning.
我试图ColumnX在 Data 以\.
是like '\%'我要找的吗？但\必须在开始。
回答by Erwin Brandstetter
The backslash \can have special meaning in LIKEpatterns. It's the default ESCAPEcharacter in PostgreSQLor MySQL- but not in Oracleor SQL Server. (Can be modified with an added ESCAPEclause in subtly varying ways, follow link for your RDBMS.)
反斜杠\在LIKE模式中可以具有特殊含义。它是PostgreSQL或MySQL 中的默认ESCAPE字符- 但不是Oracle或SQL Server。（可以通过添加的子句以细微变化的方式进行修改，请按照您的 RDBMS 的链接进行修改。）ESCAPE
In addition to that, PostgreSQLused to interpret POSIX-style escapes in strings (a.k.a. "C escape syntax") before version 9.1 and MySQLstill does in version 8.0). There you have to double \to \\to get an ordinary backslash.
除此之外，PostgreSQL用于在 9.1 版之前解释字符串中的 POSIX 样式转义（又名“C 转义语法”），而MySQL在 8.0 版中仍然如此）。在那里，你必须仔细\来\\获得一个普通的反斜杠。
According to standard SQL, \is nota meta character in strings. PostgreSQL eventually switched to standard behavior and introduced a special escape-string-syntax with E''and the config settings standard_conforming_stringsand escape_string_warningto still allow escaped string when needed.
根据标准SQL，\是不是在串的元字符。PostgreSQL 最终切换到标准行为并引入了特殊的转义字符串语法E''和配置设置，standard_conforming_strings并escape_string_warning在需要时仍然允许转义字符串。
Since Postgres 9.1standard_conforming_strings = onby default. So you write:
默认情况下从Postgres 9.1 开始standard_conforming_strings = on。所以你写：
... col LIKE '\%' -- double once to get 1 literal backslash in LIKE pattern
Else you have to write:
否则你必须写：
... col LIKE E'\\%' -- double twice to also disable special meaning as escape char
On top of that, \also has special meaning in many client programs and programming languages. If strings get interpreted before they even reach the database engine, you may have to double the \another time (or escape it in some other fashion). See this related question, for instance.
最重要的是，\在许多客户端程序和编程语言中也具有特殊含义。如果字符串在它们到达数据库引擎之前就被解释了，你可能不得\不再重复一次（或以其他方式转义它）。例如，请参阅此相关问题。
回答by Korhan Ozturk
Indeed '\%' is what you need. The following statement brings all the data where columnX starts with '\'.
确实 '\%' 正是您所需要的。以下语句包含 columnX 以 '\' 开头的所有数据。
select * from table_name where columnX like '\%'
回答by Fahim Parkar
try this...
尝试这个...
select * from myTable where ColumnX like '\%'
select * from myTable where ColumnX like '\%'
Good Luck!!!
祝你好运！！！
回答by Royi Namir
this is what you need
这就是你所需要的
