Transact-sql 数据类型 char ，varchar，nchar等最大多少KB?
SQL\u6570\u636e\u7c7b\u578bnchar\uff0cchar\uff0cvarchar\u4e0envarchar\u533a\u522bnchar\u4e0echar\u662f\u76f8\u4f3c\u7684\uff0cnvarchar\u4e0evarchar\u662f\u76f8\u4f3c\u7684\u3002
char\u7c7b\u578b\uff1a \u5bf9\u82f1\u6587(ASCII)\u5b57\u7b26\u5360\u75281\u4e2a\u5b57\u8282\uff0c\u5bf9\u4e00\u4e2a\u6c49\u5b57\u5360\u75282\u4e2a\u5b57\u8282\uff0cCHAR\u5b58\u50a8\u5b9a\u957f\u6570\u636e\u5f88\u65b9\u4fbf\uff0cCHAR\u5b57\u6bb5\u4e0a\u7684\u7d22\u5f15\u6548\u7387\u7ea7\u9ad8\uff0c\u6bd4\u5982\u5b9a\u4e49 char(10)\uff0c\u90a3\u4e48\u4e0d\u8bba\u4f60\u5b58\u50a8\u7684\u6570\u636e\u662f\u5426\u8fbe\u5230\u4e8610\u4e2a\u5b57\u8282\uff0c\u90fd\u8981\u5360\u53bb10\u4e2a\u5b57\u8282\u7684\u7a7a\u95f4\uff0c\u4e0d\u591f\u7684\u5b57\u7b26\u7528\u7a7a\u683c\u53bb\u586b\u3002\u56e0\u4e3a\u662f\u56fa\u5b9a\u957f\u5ea6\uff0c\u6240\u4ee5\u901f\u5ea6\u6548\u7387\u9ad8\u3002
Varchar\u7c7b\u578b\uff1aVarchar \u7684\u7c7b\u578b\u4e0d\u4ee5\u7a7a\u683c\u586b\u6ee1\uff0c\u6bd4\u5982varchar(100)\uff0c\u4f46\u5b83\u7684\u503c\u53ea\u662f"qian",\u5219\u5b83\u7684\u503c\u5c31\u662f"qian"
\u800cchar \u4e0d\u4e00\u6837\uff0c\u6bd4\u5982char(100),\u5b83\u7684\u503c\u662f"qian"\uff0c\u800c\u5b9e\u9645\u4e0a\u5b83\u5728\u6570\u636e\u5e93\u4e2d\u662f"qian "(qian\u540e\u5171\u670996\u4e2a\u7a7a\u683c\uff0c\u5c31\u662f\u628a\u5b83\u586b\u6ee1\u4e3a100\u4e2a\u5b57\u8282)\u3002
\u7531\u4e8echar\u662f\u4ee5\u56fa\u5b9a\u957f\u5ea6\u7684\uff0c\u6240\u4ee5\u5b83\u7684\u901f\u5ea6\u4f1a\u6bd4varchar\u5feb\u5f97\u591a\uff01\u4f46\u7a0b\u5e8f\u5904\u7406\u8d77\u6765\u8981\u9ebb\u70e6\u4e00\u70b9\uff0c\u8981\u7528trim\u4e4b\u7c7b\u7684\u51fd\u6570\u628a\u4e24\u8fb9\u7684\u7a7a\u683c\u53bb\u6389\uff01
VARCHAR\u5b58\u50a8\u53d8\u957f\u6570\u636e\uff0c\u4f46\u5b58\u50a8\u6548\u7387\u6ca1\u6709CHAR\u9ad8\u3002\u5982\u679c\u4e00\u4e2a\u5b57\u6bb5\u53ef\u80fd\u7684\u503c\u662f\u4e0d\u56fa\u5b9a\u957f\u5ea6\u7684\uff0c\u6211\u4eec\u53ea\u77e5\u9053\u5b83\u4e0d\u53ef\u80fd\u8d85\u8fc710\u4e2a\u5b57\u7b26\uff0c\u628a\u5b83\u5b9a\u4e49\u4e3a VARCHAR(10)\u662f\u6700\u5408\u7b97\u7684\u3002VARCHAR\u7c7b\u578b\u7684\u5b9e\u9645\u957f\u5ea6\u662f\u5b83\u7684\u503c\u7684\u5b9e\u9645\u957f\u5ea6+1\u3002\u4e3a\u4ec0\u4e48\u201c+1\u201d\u5462\uff1f\u8fd9\u4e00\u4e2a\u5b57\u8282\u7528\u4e8e\u4fdd\u5b58\u5b9e\u9645\u4f7f\u7528\u4e86\u591a\u5927\u7684\u957f\u5ea6\u3002
nchar\u7c7b\u578b\u548cNvarchar\u7c7b\u578b\u662f\u600e\u4e48\u4e00\u56de\u4e8b\u5462\uff1f\u4e3a\u4e86\u4e0e\u5176\u4ed6\u591a\u79cd\u5b57\u7b26\u7684\u8f6c\u6362\uff0c\u5982\u4e2d\u6587\uff0c\u97f3\u6807\u7b49\uff0c\u5bf9\u6bcf\u4e2a\u82f1\u6587(ASCII)\u5b57\u7b26\u90fd\u5360\u75282\u4e2a\u5b57\u8282\uff0c\u5bf9\u4e00\u4e2a\u6c49\u5b57\u4e5f\u5360\u7528\u4e24\u4e2a\u5b57\u8282\uff0c\u6240\u6709\u7684\u5b57\u7b26\u90fd\u5360\u75282\u4e2a\u5b57\u8282\u3002
\u5173\u4e8e\u957f\u5ea6\u4e0e\u6c49\u5b57
varchar(100)/char(100)\u80fd\u5b5850\u4e2a\u6c49\u5b57\uff0cnvarchar(100)/nchar(100)\u80fd\u5b58100\u4e2a\u6c49\u5b57\u3002
\u8fd9\u4e2a\u63d0\u95ee\u6709\u70b9\u95ee\u9898\u54e6\uff0c\u7b80\u5355\u7684\u8bb2\u662f\u8fd9\u6837\u7684 1\u3001 char(n),varchar(n)\u662f\u957f\u5ea6\u4e3a n \u4e2a\u5b57\u8282\u7684\u53ef\u53d8\u957f\u5ea6\u4e14\u975e Unicode \u7684\u5b57\u7b26\u6570\u636e\u3002n \u5fc5\u987b\u662f\u4e00\u4e2a\u4ecb\u4e8e 1 \u548c 8,000 \u4e4b\u95f4\u7684\u6570\u503c\u3002\u5b58\u50a8\u5927\u5c0f\u4e3a\u8f93\u5165\u6570\u636e\u7684\u5b57\u8282\u7684\u5b9e\u9645\u957f\u5ea6\uff0c\u800c\u4e0d\u662f n \u4e2a\u5b57\u8282\u30022\u3001nchar(n),nvarchar(n)
\u5305\u542b n \u4e2a\u5b57\u7b26\u7684\u53ef\u53d8\u957f\u5ea6 Unicode \u5b57\u7b26\u6570\u636e\u3002n \u7684\u503c\u5fc5\u987b\u4ecb\u4e8e 1 \u4e0e 4,000 \u4e4b\u95f4\u3002\u5b57\u8282\u7684\u5b58\u50a8\u5927\u5c0f\u662f\u6240\u8f93\u5165\u5b57\u7b26\u4e2a\u6570\u7684\u4e24\u500d\u3002
\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5982\u679c\u5b9a\u4e49varchar(10) \u8fd9\u91cc\u53ef\u4ee5\u6700\u591a\u53ef\u4ee5\u5b58\u653e10\u4e2a\u82f1\u6587\u5b57\u6bcd\u548c5\u4e2a\u4e2d\u6587\u6c49\u5b57
nvarchar(10) \u8fd9\u91cc\u53ef\u4ee5\u6700\u591a\u53ef\u4ee5\u5b58\u653e10\u4e2a\u82f1\u6587\u5b57\u6bcd\u548c10\u4e2a\u4e2d\u6587\u6c49\u5b57
只知道
CHAR VARCHAR最长都是8000个字符
NCHAR NVARCHAR最长都是4000个字符
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1024个英文字符是1K 也就是8K不到和4K不到
扩展阅读：动 transact-sql 调试器 ... sql和python哪个难学 ... sql server ... sql编程入门自学 ... segment ... transaction ... 执行transact sql语句异常 ... microsoft ... transact sql创建数据库 ...
