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TD-457: string cannot be truncated automatically

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Ping Xiao 2020-06-01 15:11:38 +08:00
parent 34e345e4d8
commit 61b4bdb6b3
2 changed files with 4 additions and 4 deletions
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4
documentation/webdocs/markdowndocs/TAOS SQL-ch.md
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@ -63,11 +63,11 @@ TDengine缺省的时间戳是毫秒精度，但通过修改配置参数enableMic
| 3 | BIGINT | 8 | 长整型，范围 [-2^63+1, 2^63-1], -2^63用于NULL |
| 4 | FLOAT | 4 | 浮点型，有效位数6-7，范围 [-3.4E38, 3.4E38] |
| 5 | DOUBLE | 8 | 双精度浮点型，有效位数15-16，范围 [-1.7E308, 1.7E308] |
| 6 | BINARY | 自定义 | 用于记录字符串，理论上，最长可以有65526字节，但由于每行数据最多64K字节，实际上限一般小于理论值。 binary仅支持字符串输入，字符串两端使用单引号引用，否则英文全部自动转化为小写。使用时须指定大小，如binary(20)定义了最长为20个字符的字符串，每个字符占1byte的存储空间。如果用户字符串超出20字节，将被自动截断。对于字符串内的单引号，可以用转义字符反斜线加单引号来表示， 即 **\’**。 |
| 6 | BINARY | 自定义 | 用于记录字符串，理论上，最长可以有65526字节，但由于每行数据最多64K字节，实际上限一般小于理论值。 binary仅支持字符串输入，字符串两端使用单引号引用，否则英文全部自动转化为小写。使用时须指定大小，如binary(20)定义了最长为20个字符的字符串，每个字符占1byte的存储空间。如果用户字符串超出20字节将会报错。对于字符串内的单引号，可以用转义字符反斜线加单引号来表示， 即 **\’**。 |
| 7 | SMALLINT | 2 | 短整型， 范围 [-32767, 32767], -32768用于NULL |
| 8 | TINYINT | 1 | 单字节整型，范围 [-127, 127], -128用于NULL |
| 9 | BOOL | 1 | 布尔型，{true, false} |
| 10 | NCHAR | 自定义 | 用于记录非ASCII字符串，如中文字符。每个nchar字符占用4bytes的存储空间。字符串两端使用单引号引用，字符串内的单引号需用转义字符 **\’**。nchar使用时须指定字符串大小，类型为nchar(10)的列表示此列的字符串最多存储10个nchar字符，会固定占用40bytes的空间。如用户字符串长度超出声明长度，则将被自动截断。 |
| 10 | NCHAR | 自定义 | 用于记录非ASCII字符串，如中文字符。每个nchar字符占用4bytes的存储空间。字符串两端使用单引号引用，字符串内的单引号需用转义字符 **\’**。nchar使用时须指定字符串大小，类型为nchar(10)的列表示此列的字符串最多存储10个nchar字符，会固定占用40bytes的空间。如用户字符串长度超出声明长度，则将会报错。 |
**Tips**: TDengine对SQL语句中的英文字符不区分大小写，自动转化为小写执行。因此用户大小写敏感的字符串及密码，需要使用单引号将字符串引起来。

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documentation/webdocs/markdowndocs/TAOS SQL.md
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@ -39,8 +39,8 @@ The full list of data types is listed below. For string types of data, we will
| 6 | DOUBLE | 8 | A standard nullable double float type with 15-16 significant digits and a range of [-1.7E308, 1.7E308]​ |
| 7 | BOOL | 1 | A nullable boolean type, [**`true`**, **`false`**] |
| 8 | TIMESTAMP | 8 | A nullable timestamp type with the same usage as the primary column timestamp |
| 9 | BINARY(*M*) | *M* | A nullable string type whose length is *M*, any exceeded chars will be automatically truncated, the maximum length of *M* is 65526, but as maximum row size is 64K bytes, the actual upper limit will generally less than 65526. This type of string only supports ASCii encoded chars. |
| 10 | NCHAR(*M*) | 4 * *M* | A nullable string type whose length is *M*, any exceeded chars will be truncated. The **`NCHAR`** type supports Unicode encoded chars. |
| 9 | BINARY(*M*) | *M* | A nullable string type whose length is *M*, error should be threw with exceeded chars, the maximum length of *M* is 65526, but as maximum row size is 64K bytes, the actual upper limit will generally less than 65526. This type of string only supports ASCii encoded chars. |
| 10 | NCHAR(*M*) | 4 * *M* | A nullable string type whose length is *M*, error should be threw with exceeded chars. The **`NCHAR`** type supports Unicode encoded chars. |
All the keywords in a SQL statement are case-insensitive, but strings values are case-sensitive and must be quoted by a pair of `'` or `"`. To quote a `'` or a `"` , you can use the escape character `\`.