Mysql - 更改表语句以在长文本字段上创建唯一索引
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Mysql - Alter table statement to create unique index on long text field
提问by Matt Fenwick
I'm trying to create an Altercommand to create an unique_indexon the first 8000 characters. I'm not able to figure out how to add the 8000 part. Any help would be appreciated. Thanks!
我正在尝试创建一个Alter命令来unique_index在前 8000 个字符上创建一个。我无法弄清楚如何添加 8000 部分。任何帮助，将不胜感激。谢谢！
ALTER TABLE nextractor.tblhtml
ADD UNIQUE INDEX uniqueindex_InnerHTML (InnerHtml);
回答by Matt Fenwick
According to the MySQL docs, you need something like this:
根据MySQL docs，你需要这样的东西：
alter table <table_name>
add unique index <index_name> (<column_name> (8000))
This is the relevant grammar:
这是相关的语法：
| ADD [CONSTRAINT [symbol]]
UNIQUE [INDEX|KEY] [index_name]
[index_type] (index_col_name,...) [index_option] ...
and
和
index_col_name:
col_name [(length)] [ASC | DESC]
回答by rizon
ALTER TABLE nextractor.tblhtml ADD UNIQUE INDEX uniqueindex_InnerHTML (InnerHtml (8000));
ALTER TABLE nextractor.tblhtml 添加唯一索引 uniqueindex_InnerHTML (InnerHtml (8000));
