在H2中删除列的唯一约束 [英] Dropping unique constraint for column in H2
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问题描述
我尝试在h2中删除列的唯一约束,该约束以前创建为 info varchar(255)unique
。
I try to drop unique constraint for column in h2, previously created as info varchar(255) unique
.
我尝试过:
sql> alter table public_partner drop constraint (select distinct unique_index_name from in
formation_schema.constraints where table_name='PUBLIC_PARTNER' and column_list='INFO');
但没有成功(如下所示):
But with no success (as follows):
Syntax error in SQL statement "ALTER TABLE PUBLIC_PARTNER DROP CONSTRAINT ([*]SELECT DISTI
NCT UNIQUE_INDEX_NAME FROM INFORMATION_SCHEMA.CONSTRAINTS WHERE TABLE_NAME='PUBLIC_PARTNER
' AND COLUMN_LIST='INFO') "; expected "identifier"; SQL statement:
alter table public_partner drop constraint (select distinct unique_index_name from informa
tion_schema.constraints where table_name='PUBLIC_PARTNER' and column_list='INFO') [42001-1
60]
应如何正确删除此约束?
How this constraint should be correctly removed?
顺便说一句:
sql> (select unique_index_name from information_schema.constraints where table_name='PUBLI
C_PARTNER' and column_list='INFO');
UNIQUE_INDEX_NAME
CONSTRAINT_F574_INDEX_9
(1 row, 0 ms)
似乎返回了正确的输出。
seems to return a correct output.
推荐答案
在SQL语言中,标识符名称不能是表达式。您需要运行两个语句:
In the SQL language, identifier names can't be expressions. You need to run two statements:
select distinct constraint_name from information_schema.constraints
where table_name='PUBLIC_PARTNER' and column_list='INFO'
,然后获取标识符名称,并运行语句
and then get the identifier name, and run the statement
ALTER TABLE PUBLIC_PARTNER DROP CONSTRAINT <xxx>
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