{"Entry":{"collection":"lock","key":"for-update","name":"FOR UPDATE","aliases":[],"metadata":{"abbrev":"FU","content_hash":"a9f3719df1eb261b45b07e2ed5d7b7922ee7ed28f62ca0ac8ed127b0d496ea63","derived_content_hash":"e85bc30beff67233f8bea464bd9a57fc6cee26a06fea19011f90d8b362332730","imported_at":"2026-09-27T17:58:01.278734+08:00","name":"FOR UPDATE","name_zh":"FOR UPDATE","position":11,"repair_provenance":{"original_source_revision":"10:f4e8f137bfb08a664c8288824c1e36b5143ac875;11:170e416034ec0231d9e9238f2577eeb76ca8d181;12:3f302f0ed06f69c5ebd33d4df95895323a3cbef6;13:05f6c9ec2c475fae8fdd56ae40bd01afcf70d1f2;14:fba35c7c28a567839faba867db0808564c0a66db;15:0351991b8e7c7b64382e2f30ce581a8f276590a6;16:dcc37b7099a9f3cf2c75167d8dc92e75f96bc1fa;17:163288afd32a448244c8df75b3c33181aadd7f20;18:753057e340da8f22e57c9a409ea7a235fd6a46bd;19:b73d13c32c834a2c8e1c60cb92f79530376cedf1;20:2c10c2ce4d7bcd57543a49ab402af02a39724e0a","receipt_sha256":"0731d0999d0d7abcc0f2c95d12204ec8e890a217d5e6c11a3dd345cfb8fcf350","repair":"wiki-repair-20261023"},"scope":"row","slug":"for-update","source_rev":"wiki-repair-20261023:5b7bf4985fa2adf08e1220846d0e4c7453eacf090f4368ec52d70ecf11659def","summary":"FOR UPDATE causes the rows retrieved by the SELECT statement to be locked as though for update. 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That is, other transactions that attempt UPDATE, DELETE, SELECT FOR UPDATE, SELECT FOR NO KEY UPDATE, SELECT FOR SHARE or SELECT FOR KEY SHARE of these rows will be blocked until the current transaction ends; conversely, SELECT FOR UPDATE will wait for a concurrent transaction that has run any of those commands on the same row, and will then lock and return the updated row (or no row, if the row was deleted). Within a REPEATABLE READ or SERIALIZABLE transaction, however, an error will be thrown if a row to be locked has changed since the transaction started. For further discussion see Data Consistency Checks at the Application Level.","The FOR UPDATE lock mode is also acquired by any DELETE on a row, and also by an UPDATE that modifies the values of certain columns. 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class=\"command\"\u003eUPDATE\u003c/code\u003e、\u003ccode class=\"command\"\u003eDELETE\u003c/code\u003e、\u003ccode class=\"command\"\u003eSELECT FOR UPDATE\u003c/code\u003e、\u003ccode class=\"command\"\u003eSELECT FOR NO KEY UPDATE\u003c/code\u003e、\u003ccode class=\"command\"\u003eSELECT FOR SHARE\u003c/code\u003e 或 \u003ccode class=\"command\"\u003eSELECT FOR KEY SHARE\u003c/code\u003e 的事务，都会被阻塞直到当前事务结束。反过来，\u003ccode class=\"command\"\u003eSELECT FOR UPDATE\u003c/code\u003e 也会等待已经在同一行上执行过上述任一命令的并发事务，并随后锁定并返回更新后的那一行（或者不返回任何行，因为该行可能已被删除）。不过，在 \u003ccode class=\"literal\"\u003eREPEATABLE READ\u003c/code\u003e 或 \u003ccode class=\"literal\"\u003eSERIALIZABLE\u003c/code\u003e 事务中，如果要锁定的行自事务开始以来已经发生变化，就会抛出错误。进一步讨论见\u003ca class=\"xref\" href=\"/zh/docs/18/applevel-consistency.html\" title=\"13.4. 应用级别的数据一致性检查\"\u003e第 13.4 节\u003c/a\u003e。\n        \u003c/p\u003e\u003cp\u003e\n\u003ccode class=\"literal\"\u003eFOR UPDATE\u003c/code\u003e 锁模式也会被对某一行的任何 \u003ccode 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