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28 lines
1.1 KiB
Markdown
28 lines
1.1 KiB
Markdown
---
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toc_priority: 39
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toc_title: DELETE
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---
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# ALTER TABLE … DELETE 语句 {#alter-mutations}
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``` sql
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ALTER TABLE [db.]table [ON CLUSTER cluster] DELETE WHERE filter_expr
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```
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删除匹配指定过滤表达式的数据。实现为[突变](../../../sql-reference/statements/alter/index.md#mutations).
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!!! note "备注"
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`ALTER TABLE`前缀使得这个语法不同于大多数其他支持SQL的系统。它的目的是表示，与OLTP数据库中的类似查询不同，这是一个不为经常使用而设计的繁重操作。
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`filter_expr` 的类型必须是`UInt8`。该查询删除表中该表达式接受非零值的行。
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一个查询可以包含多个用逗号分隔的命令。
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查询处理的同步性由[mutations_sync](../../../operations/settings/settings.md#mutations_sync)设置定义。缺省情况下，是异步的。
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**详见**
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- [突变](../../../sql-reference/statements/alter/index.md#mutations)
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- [ALTER查询的同步性](../../../sql-reference/statements/alter/index.md#synchronicity-of-alter-queries)
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- [mutations_sync](../../../operations/settings/settings.md#mutations_sync) setting
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