\u89e6\u53d1\u5668\uff0c\u6307\u4e00\u6bb5\u4ee3\u7801\uff0c\u5f53\u89e6\u53d1\u67d0\u4e2a\u4e8b\u4ef6\u65f6\uff0c\u81ea\u52a8\u6267\u884c\u8fd9\u4e9b\u4ee3\u7801\u3002
\n\u4f7f\u7528\u573a\u666f\uff1a
\n1\u3001\t\u53ef\u4ee5\u901a\u8fc7\u6570\u636e\u5e93\u4e2d\u7684\u76f8\u5173\u8868\u5b9e\u73b0\u7ea7\u8054\u66f4\u6539\u3002
\n2\u3001\t\u5b9e\u65f6\u76d1\u63a7\u67d0\u5f20\u8868\u4e2d\u7684\u67d0\u4e2a\u5b57\u6bb5\u7684\u66f4\u6539\u800c\u9700\u8981\u505a\u51fa\u76f8\u5e94\u7684\u5904\u7406\u3002
\n3\u3001\t\u4f8b\u5982\u53ef\u4ee5\u751f\u6210\u67d0\u4e9b\u4e1a\u52a1\u7684\u7f16\u53f7\u3002
\n4\u3001\t\u6ce8\u610f\u4e0d\u8981\u6ee5\u7528\uff0c\u5426\u5219\u4f1a\u9020\u6210\u6570\u636e\u5e93\u53ca\u5e94\u7528\u7a0b\u5e8f\u7684\u7ef4\u62a4\u56f0\u96be\u3002
\nMySQL\u4e2d\u5b57\u6bb5\u4e3a\u4ec0\u4e48\u8981\u6c42\u5b9a\u4e49\u4e3anot null?
\nnull\u503c\u4f1a\u5360\u7528\u66f4\u591a\u7684\u5b57\u8282\uff0c\u5e76\u4e14null\u6709\u5f88\u591a\u5751\u7684\u3002
\nMySQL\u4e2d\u4e00\u6761SQL\u8bed\u53e5\u5728MySQL\u4e2d\u5982\u4f55\u6267\u884c\u7684\uff1f
\n1\u3001\t\u5148\u68c0\u67e5\u8be5\u8bed\u53e5\u662f\u5426\u6709\u6743\u9650
\n2\u3001\t\u5982\u679c\u6ca1\u6709\u6743\u9650\uff0c\u76f4\u63a5\u8fd4\u56de\u9519\u8bef\u4fe1\u606f
\n3\u3001\t\u5982\u679c\u6709\u6743\u9650\uff0c\u5728MySQL8.0\u7248\u672c\u4ee5\u524d\uff0c\u4f1a\u5148\u67e5\u8be2\u7f13\u5b58\u3002
\n4\u3001\t\u5982\u679c\u6ca1\u6709\u7f13\u5b58\uff0c\u5206\u6790\u5668\u8fdb\u884c\u8bcd\u6cd5\u5206\u6790\uff0c\u63d0\u53d6sql\u8bed\u53e5select\u7b49\u7684\u5173\u952e\u5143\u7d20\u3002\u7136\u540e\u5224\u65adsql\u8bed\u53e5\u662f\u5426\u6709\u8bed\u6cd5\u9519\u8bef\uff0c\u6bd4\u5982\u5173\u952e\u8bcd\u662f\u5426\u6b63\u786e\u7b49\u7b49\u3002
\n5\u3001\t\u4f18\u5316\u5668\u8fdb\u884c\u786e\u5b9a\u6267\u884c\u65b9\u6848
\n6\u3001\t\u8fdb\u884c\u6743\u9650\u6821\u9a8c\uff0c\u5982\u679c\u6ca1\u6709\u6743\u9650\u5c31\u76f4\u63a5\u8fd4\u56de\u9519\u8bef\u4fe1\u606f\uff0c\u5982\u679c\u6709\u6743\u9650\u5c31\u4f1a\u8c03\u7528\u6570\u636e\u5e93\u5f15\u64ce\u63a5\u53e3\uff0c\u8fd4\u56de\u6267\u884c\u7ed3\u679c\u3002
\nMySQL\u4e2dselect for update\u6709\u4ec0\u4e48\u542b\u4e49\uff0c\u4f1a\u9501\u8868\u8fd8\u662f\u9501\u884c\u8fd8\u662f\u5176\u4ed6\uff1f
\nselect for update\u662f\u4e3a\u4e86\u5728\u67e5\u8be2\u65f6\uff0c\u907f\u514d\u5176\u4ed6\u7528\u6237\u4ee5\u8be5\u8868\u8fdb\u884c\u63d2\u5165\uff0c\u4fee\u6539\u6216\u5220\u9664\u7b49\u64cd\u4f5c\uff0c\u9020\u6210\u8868\u7684\u4e0d\u4e00\u81f4\u6027
\n\u7ed9\u4f60\u4e3e\u51e0\u4e2a\u4f8b\u5b50\uff1a
\nselect * from t for update\u4f1a\u7b49\u5f85\u884c\u9501\u91ca\u653e\u4e4b\u540e\uff0c\u8fd4\u56de\u67e5\u8be2\u7ed3\u679c\u3002
\nselect * from t for update nowait\u4e0d\u7b49\u5f85\u884c\u9501\u91ca\u653e\uff0c\u63d0\u793a\u9501\u51b2\u7a81\uff0c\u4e0d\u8fd4\u56de\u7ed3\u679c
\nselect * from t for update wait 5\u7b49\u5f855\u79d2\uff0c\u82e5\u884c\u9501\u4ecd\u672a\u91ca\u653e\uff0c\u5219\u63d0\u793a\u9501\u51b2\u7a81\uff0c\u4e0d\u8fd4\u56de\u7ed3\u679c
\nselect * from t for update skip locked\u67e5\u8be2\u8fd4\u56de\u67e5\u8be2\u7ed3\u679c\uff0c\u4f46\u5ffd\u7565\u6709\u884c\u9501\u7684\u8bb0\u5f55
\n\u5206\u6210\u4e24\u7c7b\uff1a\u52a0\u9501\u8303\u56f4\u5b50\u53e5\u548c\u52a0\u9501\u884c\u4e3a\u5b50\u53e5
\n\u52a0\u9501\u8303\u56f4\u5b50\u53e5\uff1a\u5728select\u2026for update\u4e4b\u540e\uff0c\u53ef\u4ee5\u4f7f\u7528of\u5b50\u53e5\u9009\u62e9\u5bf9select\u7684\u7279\u5b9a\u6570\u636e\u8868\u8fdb\u884c\u52a0\u9501\u64cd\u4f5c\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u4e0d\u4f7f\u7528of\u5b50\u53e5\u8868\u793a\u5728select\u6240\u6709\u7684\u6570\u636e\u8868\u4e2d\u52a0\u9501
\n\u52a0\u9501\u884c\u4e3a\u5b50\u53e5\uff1a\u5f53\u6211\u4eec\u8fdb\u884cfor update\u7684\u64cd\u4f5c\u65f6\uff0c\u4e0e\u666e\u901aselect\u5b58\u5728\u5f88\u5927\u4e0d\u540c\u3002\u4e00\u822cselect \u662f\u4e0d\u9700\u8981\u8003\u8651\u6570\u636e\u662f\u5426\u88ab\u9501\u5b9a\uff0c\u6700\u591a\u6839\u636e\u591a\u7248\u672c\u4e00\u81f4\u8bfb\u7684\u7279\u6027\u8bfb\u53d6\u4e4b\u524d\u7684\u7248\u672c\u3002\u52a0\u5165for update\u4e4b\u540e\uff0cOracle\u5c31\u8981\u6c42\u542f\u52a8\u4e00\u4e2a\u65b0\u4e8b\u52a1\uff0c\u5c1d\u8bd5\u5bf9\u6570\u636e\u8fdb\u884c\u52a0\u9501\u3002\u5982\u679c\u5f53\u524d\u5df2\u7ecf\u88ab\u52a0\u9501\uff0c\u9ed8\u8ba4\u7684\u884c\u4e3a\u5fc5\u7136\u662fblock\u7b49\u5f85\u3002\u4f7f\u7528nowait\u5b50\u53e5\u7684\u4f5c\u7528\u5c31\u662f\u907f\u514d\u8fdb\u884c\u7b49\u5f85\uff0c\u5f53\u53d1\u73b0\u8bf7\u6c42\u52a0\u9501 \u8d44\u6e90\u88ab\u9501\u5b9a\u672a\u91ca\u653e\u7684\u65f6\u5019\uff0c\u76f4\u63a5\u62a5\u9519\u8fd4\u56de\u3002
\n\u5728\u65e5\u5e38\u4e2d\uff0c\u6211\u4eec\u5bf9for update\u7684\u4f7f\u7528\u8fd8\u662f\u6bd4\u8f83\u666e\u904d\u7684\uff0c\u7279\u522b\u662f\u5728\u5982pl\/sql developer\u4e2d\u624b\u5de5\u4fee\u6539\u6570\u636e\u3002\u6b64\u65f6\u53ea\u662f\u89c9\u5f97\u65b9\u4fbf\uff0c\u800c\u5bf9for update\u771f\u6b63\u7684\u542b\u4e49\u7f3a\u4e4f\u7406\u89e3\u3002
\nFor update\u662fOracle\u63d0\u4f9b\u7684\u624b\u5de5\u63d0\u9ad8\u9501\u7ea7\u522b\u548c\u8303\u56f4\u7684\u7279\u4f8b\u8bed\u53e5\u3002Oracle\u7684\u9501\u673a\u5236\u662f\u76ee\u524d\u5404\u7c7b\u578b\u6570\u636e\u5e93\u9501\u673a\u5236\u4e2d\u6bd4\u8f83\u4f18\u79c0\u7684\u3002\u6240\u4ee5\uff0cOracle\u8ba4\u4e3a\u4e00\u822c\u4e0d\u9700\u8981\u7528\u6237\u548c\u5e94\u7528\u76f4\u63a5\u8fdb\u884c\u9501\u7684\u63a7\u5236\u548c\u63d0\u5347\u3002\u751a\u81f3\u8ba4\u4e3a\u6b7b\u9501\u8fd9\u7c7b\u9501\u76f8\u5173\u95ee\u9898\u7684\u51fa\u73b0\u573a\u666f\uff0c\u5927\u90fd\u4e0e\u624b\u5de5\u63d0\u5347\u9501\u6709\u5173\u3002
\n\u6240\u4ee5\uff0cOracle\u5e76\u4e0d\u63a8\u8350\u4f7f\u7528for update\u4f5c\u4e3a\u65e5\u5e38\u5f00\u53d1\u4f7f\u7528\u3002\u800c\u4e14\uff0c\u5728\u5e73\u65f6\u5f00\u53d1\u548c\u8fd0\u7ef4\u4e2d\uff0c\u4f7f\u7528\u4e86 for update\u5374\u5fd8\u8bb0\u63d0\u4ea4\uff0c\u4f1a\u5f15\u8d77\u5f88\u591a\u9501\u8868\u6545\u969c\u3002\u90a3\u4e48\uff0c\u4ec0\u4e48\u65f6\u5019\u9700\u8981\u4f7f\u7528for update?\u5c31\u662f\u90a3\u4e9b\u9700\u8981\u4e1a\u52a1\u5c42\u9762\u6570\u636e\u72ec\u5360\u65f6\uff0c\u53ef\u4ee5\u8003\u8651\u4f7f\u7528for updateo\u573a\u666f\u4e0a\uff0c\u6bd4\u5982\u706b\u8f66\u7968\u8ba2\u7968\uff0c\u5728\u5c4f\u5e55\u4e0a\u663e\u793a\u90ae\u7968\uff0c\u800c\u771f\u6b63\u8fdb\u884c\u51fa\u7968\u65f6\uff0c\u9700\u8981\u91cd\u65b0\u786e\u5b9a\u4e00\u4e0b\u8fd9\u4e2a\u6570\u636e\u6ca1\u6709\u88ab\u5176\u4ed6\u5ba2\u6237\u7aef\u4fee\u6539\u3002\u6240\u4ee5\uff0c\u5728\u8fd9\u4e2a\u786e\u8ba4\u8fc7\u7a0b\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528for update\u3002\u8fd9\u662f\u7edf\u4e00\u7684\u89e3\u51b3\u65b9\u6848\u95ee\u9898\uff0c\u9700\u8981\u524d\u671f\u6709\u6240\u51c6\u5907\u3002
\nMySQL \u4e2d varchar (50)\u4e2d 50 \u7684\u6db5\u4e49\uff1f
\n\u6700\u591a\u5b58\u653e50\u4e2a\u5b57\u7b26\uff0cvarchar(50)\u548c(200)\u5b58\u50a8hello\u6240\u5360\u7a7a\u95f4\u4e00\u6837\uff0c\u4f46\u540e\u8005\u5728\u6392\u5e8f\u65f6\u4f1a\u6d88\u8017\u66f4\u591a\u5185\u5b58,\u56e0\u4e3aorder by col\u91c7\u7528fixed_length\u8ba1\u7b97col\u957f\u5ea6(memory\u5f15\u64ce\u4e5f\u4e00\u6837)\u3002\u5728\u65e9\u671fMySQL\u7248\u672c\u4e2d\uff0c50\u4ee3\u8868\u5b57\u8282\u6570\uff0c\u73b0\u5728\u4ee3\u8868\u5b57\u7b26\u6570\u3002
\nMySQL \u4e2d fetch_array \u548c MySQL_fetch_object \u7684\u533a\u522b\u662f\u4ec0\u4e48\uff1f
\n\u4ee5\u4e0b\u662f MySQL_fetch_array \u548c MySQL_fetch_object \u7684\u533a\u522b\uff1a
\nMySQL_fetch_array()-\u5c06\u7ed3\u679c\u884c\u4f5c\u4e3a\u5173\u8054\u6570\u7ec4\u6216\u6765\u81ea\u6570\u636e\u5e93\u7684\u5e38\u89c4\u6570\u7ec4\u8fd4\u56de\u3002
\nMySQL_fetch_object -\u4ece\u6570\u636e\u5e93\u8fd4\u56de\u7ed3\u679c\u884c\u4f5c\u4e3a\u5bf9\u8c61\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u89e6\u53d1\u5668\uff0c\u6307\u4e00\u6bb5\u4ee3\u7801\uff0c\u5f53\u89e6\u53d1\u67d0\u4e2a\u4e8b\u4ef6\u65f6\uff0c\u81ea\u52a8\u6267\u884c\u8fd9\u4e9b\u4ee3\u7801\u3002 \u4f7f\u7528\u573a\u666f\uff1a 1\u3001 \u53ef\u4ee5\u901a\u8fc7\u6570\u636e\u5e93\u4e2d\u7684\u76f8\u5173\u8868\u5b9e\u73b0\u7ea7\u8054\u66f4 […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[102],"tags":[],"class_list":["post-8765","post","type-post","status-publish","format-standard","hentry","category-db"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/8765","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=8765"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/8765\/revisions"}],"predecessor-version":[{"id":8766,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/8765\/revisions\/8766"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=8765"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=8765"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=8765"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}