{"id":135149,"date":"2024-10-31T08:15:36","date_gmt":"2024-10-31T00:15:36","guid":{"rendered":"https:\/\/server.hk\/cnblog\/135149\/"},"modified":"2024-10-31T08:15:37","modified_gmt":"2024-10-31T00:15:37","slug":"sql-ntext%e5%ad%97%e6%ae%b5%e7%9a%84%e6%9b%bf%e6%8f%9b%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/135149\/","title":{"rendered":"SQL ntext\u5b57\u6bb5\u7684\u66ff\u63db\u65b9\u6cd5"},"content":{"rendered":"<h1 id=\"sql-ntext%e5%ad%97%e6%ae%b5%e7%9a%84%e6%9b%bf%e6%8f%9b%e6%96%b9%e6%b3%95-cwjRONBlGY\">SQL ntext\u5b57\u6bb5\u7684\u66ff\u63db\u65b9\u6cd5<\/h1>\n<p>\u5728SQL Server\u4e2d\uff0cntext\u662f\u4e00\u7a2e\u7528\u65bc\u5b58\u5132\u5927\u578bUnicode\u6587\u672c\u6578\u64da\u7684\u6578\u64da\u985e\u578b\u3002\u96d6\u7136ntext\u53ef\u4ee5\u5b58\u5132\u5927\u91cf\u7684\u5b57\u7b26\uff0c\u4f46\u7531\u65bc\u5176\u67d0\u4e9b\u9650\u5236\uff0c\u8a31\u591a\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u5728\u4f7f\u7528\u6642\u6703\u9047\u5230\u6311\u6230\u3002\u96a8\u8457\u6280\u8853\u7684\u9032\u6b65\uff0cMicrosoft\u5df2\u7d93\u5efa\u8b70\u4f7f\u7528nvarchar(max)\u4f86\u66ff\u4ee3ntext\uff0c\u56e0\u70banvarchar(max)\u63d0\u4f9b\u4e86\u66f4\u597d\u7684\u6027\u80fd\u548c\u9748\u6d3b\u6027\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u6709\u6548\u5730\u66ff\u63dbntext\u5b57\u6bb5\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\u3002<\/p>\n<h2 id=\"%e7%82%ba%e4%bb%80%e9%ba%bc%e8%a6%81%e6%9b%bf%e6%8f%9bntext%e5%ad%97%e6%ae%b5-cwjRONBlGY\">\u70ba\u4ec0\u9ebc\u8981\u66ff\u63dbntext\u5b57\u6bb5<\/h2>\n<p>ntext\u5b57\u6bb5\u7684\u4e3b\u8981\u554f\u984c\u5728\u65bc\u5176\u4e0d\u652f\u6301\u67d0\u4e9b\u5b57\u7b26\u4e32\u64cd\u4f5c\uff0c\u4f8b\u5982LEN\u3001SUBSTRING\u7b49\uff0c\u9019\u4f7f\u5f97\u5728\u8655\u7406\u6587\u672c\u6578\u64da\u6642\u8b8a\u5f97\u4e0d\u4fbf\u3002\u6b64\u5916\uff0cntext\u5b57\u6bb5\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u6703\u5c0e\u81f4\u6027\u80fd\u4e0b\u964d\uff0c\u7279\u5225\u662f\u5728\u67e5\u8a62\u548c\u66f4\u65b0\u64cd\u4f5c\u4e2d\u3002\u56e0\u6b64\uff0c\u5c07ntext\u5b57\u6bb5\u66ff\u63db\u70banvarchar(max)\u662f\u63d0\u9ad8\u6578\u64da\u5eab\u6027\u80fd\u548c\u53ef\u7528\u6027\u7684\u6709\u6548\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"%e6%9b%bf%e6%8f%9bntext%e5%ad%97%e6%ae%b5%e7%9a%84%e6%ad%a5%e9%a9%9f-cwjRONBlGY\">\u66ff\u63dbntext\u5b57\u6bb5\u7684\u6b65\u9a5f<\/h2>\n<p>\u4ee5\u4e0b\u662f\u5c07ntext\u5b57\u6bb5\u66ff\u63db\u70banvarchar(max)\u7684\u57fa\u672c\u6b65\u9a5f\uff1a<\/p>\n<ol>\n<li><strong>\u5099\u4efd\u6578\u64da\uff1a<\/strong>\u5728\u9032\u884c\u4efb\u4f55\u7d50\u69cb\u6027\u66f4\u6539\u4e4b\u524d\uff0c\u52d9\u5fc5\u5099\u4efd\u6578\u64da\u5eab\uff0c\u4ee5\u9632\u6b62\u6578\u64da\u4e1f\u5931\u3002<\/li>\n<li><strong>\u5275\u5efa\u65b0\u5b57\u6bb5\uff1a<\/strong>\u5728\u8868\u4e2d\u5275\u5efa\u4e00\u500b\u65b0\u7684nvarchar(max)\u5b57\u6bb5\u3002<\/li>\n<li><strong>\u5c07\u6578\u64da\u8f49\u79fb\u5230\u65b0\u5b57\u6bb5\uff1a<\/strong>\u4f7f\u7528UPDATE\u8a9e\u53e5\u5c07ntext\u5b57\u6bb5\u4e2d\u7684\u6578\u64da\u8f49\u79fb\u5230\u65b0\u7684nvarchar(max)\u5b57\u6bb5\u3002<\/li>\n<li><strong>\u522a\u9664\u820a\u5b57\u6bb5\uff1a<\/strong>\u5728\u78ba\u8a8d\u6578\u64da\u5df2\u6210\u529f\u8f49\u79fb\u5f8c\uff0c\u53ef\u4ee5\u522a\u9664\u820a\u7684ntext\u5b57\u6bb5\u3002<\/li>\n<li><strong>\u91cd\u547d\u540d\u65b0\u5b57\u6bb5\uff1a<\/strong>\u5982\u679c\u9700\u8981\uff0c\u53ef\u4ee5\u5c07\u65b0\u5b57\u6bb5\u91cd\u547d\u540d\u70ba\u820a\u5b57\u6bb5\u7684\u540d\u7a31\u3002<\/li>\n<\/ol>\n<h2 id=\"%e7%a4%ba%e4%be%8b%e4%bb%a3%e7%a2%bc-cwjRONBlGY\">\u793a\u4f8b\u4ee3\u78bc<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff0c\u5c55\u793a\u5982\u4f55\u5c07ntext\u5b57\u6bb5\u66ff\u63db\u70banvarchar(max)\uff1a<\/p>\n<pre><code>-- \u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70baMyTable\u7684\u8868\uff0c\u4e26\u4e14\u6709\u4e00\u500bntext\u5b57\u6bb5\u540d\u70baOldNTextField\n-- \u7b2c\u4e00\u6b65\uff1a\u5275\u5efa\u4e00\u500b\u65b0\u7684nvarchar(max)\u5b57\u6bb5\nALTER TABLE MyTable ADD NewNVarCharField NVARCHAR(MAX);\n\n-- \u7b2c\u4e8c\u6b65\uff1a\u5c07\u6578\u64da\u5f9entext\u5b57\u6bb5\u8f49\u79fb\u5230\u65b0\u7684nvarchar(max)\u5b57\u6bb5\nUPDATE MyTable SET NewNVarCharField = CAST(OldNTextField AS NVARCHAR(MAX));\n\n-- \u7b2c\u4e09\u6b65\uff1a\u522a\u9664\u820a\u7684ntext\u5b57\u6bb5\nALTER TABLE MyTable DROP COLUMN OldNTextField;\n\n-- \u7b2c\u56db\u6b65\uff1a\u5982\u679c\u9700\u8981\uff0c\u91cd\u547d\u540d\u65b0\u5b57\u6bb5\nEXEC sp_rename 'MyTable.NewNVarCharField', 'OldNTextField', 'COLUMN';\n<\/code><\/pre>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-cwjRONBlGY\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u9032\u884cntext\u5b57\u6bb5\u7684\u66ff\u63db\u6642\uff0c\u9700\u6ce8\u610f\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd\u65b0\u5b57\u6bb5\u7684\u5927\u5c0f\u8db3\u5920\u5b58\u5132\u820a\u5b57\u6bb5\u4e2d\u7684\u6240\u6709\u6578\u64da\u3002<\/li>\n<li>\u5728\u8f49\u79fb\u6578\u64da\u6642\uff0c\u6aa2\u67e5\u662f\u5426\u6709\u4efb\u4f55\u6578\u64da\u640d\u5931\u6216\u8f49\u63db\u932f\u8aa4\u3002<\/li>\n<li>\u5728\u522a\u9664\u820a\u5b57\u6bb5\u4e4b\u524d\uff0c\u52d9\u5fc5\u78ba\u8a8d\u6578\u64da\u5df2\u6210\u529f\u8f49\u79fb\u3002<\/li>\n<li>\u8003\u616e\u5728\u9ad8\u5cf0\u6642\u6bb5\u4ee5\u5916\u7684\u6642\u9593\u9032\u884c\u6b64\u64cd\u4f5c\uff0c\u4ee5\u6e1b\u5c11\u5c0d\u7528\u6236\u7684\u5f71\u97ff\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-cwjRONBlGY\">\u7d50\u8ad6<\/h2>\n<p>\u66ff\u63dbntext\u5b57\u6bb5\u70banvarchar(max)\u662f\u4e00\u500b\u6709\u6548\u7684\u6578\u64da\u5eab\u512a\u5316\u7b56\u7565\uff0c\u53ef\u4ee5\u63d0\u9ad8\u6027\u80fd\u4e26\u7c21\u5316\u6578\u64da\u64cd\u4f5c\u3002\u901a\u904e\u9075\u5faa\u4e0a\u8ff0\u6b65\u9a5f\u548c\u6ce8\u610f\u4e8b\u9805\uff0c\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u53ef\u4ee5\u9806\u5229\u5b8c\u6210\u9019\u4e00\u904e\u7a0b\uff0c\u5f9e\u800c\u63d0\u5347\u6574\u9ad4\u7cfb\u7d71\u7684\u6548\u7387\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u7684\u5ba2\u6236\u3002\u7121\u8ad6\u662f <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u9084\u662f\u5176\u4ed6\u96f2\u670d\u52d9\uff0c\u6211\u5011\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u53ef\u9760\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3SQL ntext\u5b57\u6bb5\u7684\u66ff\u63db\u65b9\u6cd5\uff0c\u5b78\u7fd2\u5982\u4f55\u6709\u6548\u8655\u7406\u548c\u66f4\u65b0\u5927\u578b\u6587\u672c\u6578\u64da\uff0c\u63d0\u5347\u6578\u64da\u5eab\u64cd\u4f5c\u6548\u7387\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-135149","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/135149","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=135149"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/135149\/revisions"}],"predecessor-version":[{"id":135150,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/135149\/revisions\/135150"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=135149"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=135149"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=135149"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}