42702 — 列引用歧义（ambiguous_column）

列引用有歧义，多个表都有该列名。

英文手册覆盖始于 PostgreSQL 8.1. 来源历史与运行验证各自保留独立版本边界。

当前阅读 PG 18·选择有来源记录的版本

8.1 8.2 8.3 8.4 9.0 9.1 9.2 9.3 9.4 9.5 9.6 10 11 12 13 14 15 16 17 18 19 20

aliases: 未知
class name: Syntax Error or Access Rule Violation
condition name: ambiguous_column
lang: en
sqlstate: 42702

版本定义 PG 18

42702 — 列引用歧义

速览 {#at-a-glance}

SQLSTATE 42702 是 Class 42 中的 ambiguous_column。42702 表示列引用歧义。选定 join 使用两个真实表的 id，未限定的 SELECT id 报告 column reference "%s" is ambiguous。

含义 {#meaning}

42702 表示列引用歧义。在 colNameToVar 中，PostgreSQL 会扫描当前可见 namespace 的未限定名称。如果同一次查找中有两个可见 range-table 条目都匹配，就会在执行前以 ERROR 发出 column reference "%s" is ambiguous；选定 join 的两张真实表都暴露了 id。这个分支属于名称解析，行值是否相同不能消除歧义。

诊断 {#diagnosis}

检查别名、CTE、连接输入、lateral 可见性，以及当前查询范围内提供该名称的每个关系。即使两列值相同，未限定名称仍可能有歧义，因为 PostgreSQL 必须先解析来源再执行查询。这是解析阶段的名称解析，因此选定自动提交会话仍为 IDLE；它不同于没有匹配列的 42703。显式事务仍遵循语句级 ERROR 的通常事务状态规则。

处理 {#response}

使用稳定的表别名限定预期列（或从范围中移除非预期关系），然后核对返回行。不要依赖连接顺序或相同值“解决”歧义。如果生成 SQL 会引入别名或 CTE，应把限定写进查询构造器契约，并测试选定的来源列。

报文 {#messages}

选定的 parse_relation.c 分支以明确的 ERROR 发出主报文 column reference "%s" is ambiguous；%s 是未解析的列名，解析位置随语句上下文变化。只有客户端异常而没有服务器 SQLSTATE 和主报文时，不能据此认定 42702。

代表案例 {#case}

本页使用与运行器注册表相同的语句。执行时，syntax_schema、syntax_role 等生成名称会替换为一次性实例中的实际值。

CREATE TABLE syntax_schema.left_table (id integer);
CREATE TABLE syntax_schema.right_table (id integer);
INSERT INTO syntax_schema.left_table VALUES (1);
INSERT INTO syntax_schema.right_table VALUES (1);
SELECT id FROM syntax_schema.left_table, syntax_schema.right_table;
SELECT syntax_schema.left_table.id FROM syntax_schema.left_table, syntax_schema.right_table;

选定的 18.6 运行记录结构化诊断并通过修复断言；10.21 运行通过同一案例的具体检查。可下载的案例和证据投影分别是 42702 案例 JSON 和 作者证据。运行器清单为 verify/cases/42702/cases.json，页面 SQL 会与共享注册表核对。

版本 {#versions}

选定的自然运行范围是 PostgreSQL 18.6 与 10.21，不能据此推断所有中间版本的行为。

来源 {#sources}

src.errcodes.18.6 — fixed errcodes.txt definition at commit 724edf9bde9d356724ad384a2e196edc3c9f80f7; SHA-256 6e8de346643ba84aa3c9c6a73360acfc7b2dfb89162c06c08ce9bf5bcd5bbcba (source).
src.ambiguous-column.18.6 — src/backend/parser/parse_relation.c at REL_18_6 commit 724edf9bde9d356724ad384a2e196edc3c9f80f7; fixed blob SHA-256 0d9c88f4a8def4c2d982c33f13208590e21ecf5e6f8cd9d7faa223dc771c9a9a (source).
src.ambiguous-column.10.23 — src/backend/parser/parse_relation.c at REL_10_23 commit 02991e79f8f58bc208f05dcc8af0c62dbe0a6ea4; fixed blob SHA-256 a34f40fc93fa5df0015fe5af5ee7761ccba2d16a791cda69ae07848ed27616b5 (source).
src.calls.REL_18_6 / src.calls.REL_10_23 — fixed call scans, SHA-256 9ee8a0e81d8f0825c5c1ae45583439859a26e602bdd4ce2f2a62aa278867ccbf / 00d16d3eb01b71ccf1b245c8f3102f9d0ec9f36fb02777b8dd1b99fcb263040c.

比较版本

SQLSTATE 证据与已记录的运行版本

cases · ambiguous_column

{
  "assertions": [
    "SQLSTATE is 42702 with the ambiguous-reference diagnostic",
    "The session remains IDLE",
    "Qualifying the column returns the intended row"
  ],
  "case_id": "ambiguous_column",
  "cleanup": "Drop the case schema with an owner connection.",
  "has_snippet": true,
  "position": 0,
  "preconditions": [
    "A runner-owned disposable target is provisioned."
  ],
  "repair": "Qualify the column with its table or alias and verify the intended source.",
  "trigger": "Join two tables that both expose id and select id without qualification.",
  "versions": [
    "10",
    "18"
  ]
}

claims · identity.class-and-condition

{
  "claim_id": "identity.class-and-condition",
  "limits": "Directory identity does not identify every backend path.",
  "method": "Read fixed errcodes.txt and the locked catalogue metadata.",
  "position": 0,
  "runtime": [],
  "sources": [
    "src.errcodes.18.6"
  ],
  "statement": "42702 is the ambiguous_column condition in Class 42."
}

claims · mechanism.backend-path

{
  "claim_id": "mechanism.backend-path",
  "limits": "Other calls can use the same SQLSTATE with different context or dynamic fields.",
  "method": "Trace the resolved REL_18_6 and REL_10_23 source call records at the locked commits.",
  "position": 1,
  "runtime": [],
  "sources": [
    "src.ambiguous-column.18.6",
    "src.ambiguous-column.10.23"
  ],
  "statement": "The fixed source calls for 42702 include the mechanism and message boundary selected for this page."
}

claims · runtime.representative-case

{
  "claim_id": "runtime.representative-case",
  "limits": "This covers the selected case and targets only; it does not generalize to all drivers or intermediate releases.",
  "method": "Run the shared registry case and inspect structured diagnostics, state/recovery assertions, and cleanup.",
  "position": 2,
  "runtime": [
    "runtime.42702-syntax-latest1.latest",
    "runtime.42702-syntax-pg10.pg10"
  ],
  "sources": [
    "manifest.42702",
    "snippet-registry.42702"
  ],
  "statement": "The selected ambiguous_column case passed on isolated PostgreSQL 18.6 and 10.21 targets."
}

claims · versions.catalogue-boundary

{
  "claim_id": "versions.catalogue-boundary",
  "limits": "Definition presence is not an exact behavioral introduction.",
  "method": "Read generated facts and selected summaries.",
  "position": 3,
  "runtime": [],
  "sources": [
    "src.errcodes.18.6",
    "src.calls.REL_18_6",
    "src.calls.REL_10_23"
  ],
  "statement": "The locked catalogue records 42702; runtime scope is limited to the selected targets."
}

messages · message.ambiguous-column

{
  "limits": "",
  "message_id": "message.ambiguous-column",
  "path": "",
  "position": 0,
  "raw": {
    "id": "message.ambiguous-column",
    "primary_template": "column reference \"%s\" is ambiguous",
    "severity_source": "explicit ERROR",
    "sources": [
      "src.ambiguous-column.18.6",
      "src.ambiguous-column.10.23"
    ],
    "sqlstate": "42702"
  },
  "severity": "explicit ERROR",
  "sources": [
    "src.ambiguous-column.18.6",
    "src.ambiguous-column.10.23"
  ],
  "templates": [
    {
      "kind": "primary",
      "literal": "column reference \" \" is ambiguous",
      "position": 0,
      "role": "",
      "template": "column reference \"%s\" is ambiguous"
    }
  ]
}

runtimes · runtime.42702-syntax-latest1.latest · 18.6 (Homebrew) · passed

{
  "cases": [],
  "limits": "",
  "position": 0,
  "raw": {
    "assertions": [
      {
        "expected": "42702",
        "name": "42702 SQLSTATE",
        "observed": "42702",
        "passed": true
      },
      {
        "expected": "ERROR",
        "name": "42702 ERROR severity",
        "observed": "ERROR",
        "passed": true
      },
      {
        "expected": "column reference \"id\" is ambiguous",
        "name": "42702 primary diagnostic",
        "observed": "column reference \"id\" is ambiguous",
        "passed": true
      },
      {
        "expected": "IDLE",
        "name": "ambiguous reference leaves session usable",
        "observed": "IDLE",
        "passed": true
      },
      {
        "expected": {
          "status": "IDLE",
          "value": 1
        },
        "name": "qualified reference repairs query",
        "observed": {
          "status": "IDLE",
          "value": 1
        },
        "passed": true
      }
    ],
    "case_manifest": {
      "id": "manifest.42702",
      "kind": "local_artifact",
      "path": "verify/cases/42702/cases.json",
      "sha256": "31c6d96bb62ae0e507e1a627429d53825a5ecf30942b6df342a6ec68aadec3de",
      "source_role": "case_manifest"
    },
    "cleanup": {
      "errors": [],
      "passed": true
    },
    "environment": {
      "TimeZone": "Asia/Shanghai",
      "backend_pid": 1700,
      "binary": {
        "bindir": "/opt/homebrew/Cellar/postgresql@18/18.6/bin",
        "pg_config": "/opt/homebrew/bin/pg_config",
        "pg_config_version": "PostgreSQL 18.6 (Homebrew)",
        "postgres": "/opt/homebrew/Cellar/postgresql@18/18.6/bin/postgres"
      },
      "connection_scope": "runner-owned localhost port",
      "current_user": "runner",
      "docker": {},
      "lc_messages": "C",
      "libpq_version": "18.6",
      "locale": "en_US.UTF-8",
      "log_destination": "csvlog,jsonlog",
      "log_error_verbosity": "verbose",
      "log_min_error_statement": "error",
      "log_min_messages": "error",
      "logging_collector": "on",
      "machine": "arm64",
      "max_connections": "100",
      "platform": "macOS-26.6.2-arm64-arm-64bit-Mach-O",
      "psycopg_version": "3.3.5",
      "python_version": "3.14.6 (main, Jun 10 2026, 10:03:53) [Clang 21.0.0 (clang-2100.0.123.102)]",
      "server_encoding": "UTF8",
      "server_version": "18.6 (Homebrew)",
      "server_version_num": "180006",
      "target_kind": "latest",
      "wal_level": "logical"
    },
    "id": "runtime.42702-syntax-latest1.latest",
    "observed": {
      "connection_autocommit": true,
      "diagnostic": {
        "column_name": null,
        "constraint_name": null,
        "context": null,
        "datatype_name": null,
        "exception_type": "AmbiguousColumn",
        "internal_position": null,
        "internal_query": null,
        "message_detail": null,
        "message_hint": null,
        "message_primary": "column reference \"id\" is ambiguous",
        "schema_name": null,
        "severity": "ERROR",
        "severity_nonlocalized": "ERROR",
        "source_file": "parse_relation.c",
        "source_function": "colNameToVar",
        "source_line": "964",
        "sqlstate": "42702",
        "statement_position": "8",
        "table_name": null,
        "text": "column reference \"id\" is ambiguous\nLINE 1: SELECT id FROM \"c42702_ambiguous_column\".\"left_table\", \"c427...\n               ^"
      },
      "failed_status": "IDLE",
      "repair_status": "IDLE",
      "repair_value": 1
    },
    "raw": "verify/results/42702-syntax-latest1/latest/raw.jsonl",
    "raw_sha256": "a02b48866b59e742a175f6f4149381d97944325a4ef95bb63c5f211c73978a6a",
    "run_id": "42702-syntax-latest1",
    "server_version": "18.6 (Homebrew)",
    "server_version_num": 180006,
    "snippet_registry": {
      "id": "snippet-registry.42702",
      "kind": "local_artifact",
      "path": "verify/cases/42702/snippets.json",
      "sha256": "b8d1edca0e090bda71ee447d0750e13f460c603a479818170bdfea34716bdf17",
      "source_role": "snippet_registry"
    },
    "status": "passed",
    "summary": "verify/results/42702-syntax-latest1/latest/summary.json",
    "summary_sha256": "3f27e6d4e7ad01d6c4385f7b157caa93d96bf2d1f2e051794cfca7e7f0b3f0c8",
    "target": "latest"
  },
  "run_id": "42702-syntax-latest1",
  "runtime_id": "runtime.42702-syntax-latest1.latest",
  "server_version": "18.6 (Homebrew)",
  "status": "passed",
  "target": "latest"
}

runtimes · runtime.42702-syntax-pg10.pg10 · 10.21 (Debian 10.21-1.pgdg90+1) · passed

{
  "cases": [],
  "limits": "",
  "position": 1,
  "raw": {
    "assertions": [
      {
        "expected": "42702",
        "name": "42702 SQLSTATE",
        "observed": "42702",
        "passed": true
      },
      {
        "expected": "ERROR",
        "name": "42702 ERROR severity",
        "observed": "ERROR",
        "passed": true
      },
      {
        "expected": "column reference \"id\" is ambiguous",
        "name": "42702 primary diagnostic",
        "observed": "column reference \"id\" is ambiguous",
        "passed": true
      },
      {
        "expected": "IDLE",
        "name": "ambiguous reference leaves session usable",
        "observed": "IDLE",
        "passed": true
      },
      {
        "expected": {
          "status": "IDLE",
          "value": 1
        },
        "name": "qualified reference repairs query",
        "observed": {
          "status": "IDLE",
          "value": 1
        },
        "passed": true
      }
    ],
    "case_manifest": {
      "id": "manifest.42702",
      "kind": "local_artifact",
      "path": "verify/cases/42702/cases.json",
      "sha256": "31c6d96bb62ae0e507e1a627429d53825a5ecf30942b6df342a6ec68aadec3de",
      "source_role": "case_manifest"
    },
    "cleanup": {
      "errors": [],
      "passed": true
    },
    "environment": {
      "TimeZone": "Etc/UTC",
      "backend_pid": 79,
      "binary": {},
      "connection_scope": "runner-owned localhost port",
      "current_user": "postgres",
      "docker": {
        "architecture": "arm64",
        "command": "/usr/local/bin/docker",
        "digest": "sha256:b2baf8998630663d21370da06387c950e587071bdd307ee34e661cdcc7442bcc",
        "id": "sha256:b2baf8998630663d21370da06387c950e587071bdd307ee34e661cdcc7442bcc",
        "image": "postgres:10",
        "image_created": "2022-06-23T09:11:18.374607054Z",
        "image_ref": "postgres@sha256:b2baf8998630663d21370da06387c950e587071bdd307ee34e661cdcc7442bcc",
        "log_destination": "csvlog",
        "os": "linux",
        "repo_digests": [
          "postgres@sha256:b2baf8998630663d21370da06387c950e587071bdd307ee34e661cdcc7442bcc"
        ]
      },
      "lc_messages": "en_US.utf8",
      "libpq_version": "18.6",
      "locale": "en_US.UTF-8",
      "log_destination": "csvlog",
      "log_error_verbosity": "verbose",
      "log_min_error_statement": "error",
      "log_min_messages": "error",
      "logging_collector": "on",
      "machine": "arm64",
      "max_connections": "100",
      "platform": "macOS-26.6.2-arm64-arm-64bit-Mach-O",
      "psycopg_version": "3.3.5",
      "python_version": "3.14.6 (main, Jun 10 2026, 10:03:53) [Clang 21.0.0 (clang-2100.0.123.102)]",
      "server_encoding": "UTF8",
      "server_version": "10.21 (Debian 10.21-1.pgdg90+1)",
      "server_version_num": "100021",
      "target_kind": "pg10",
      "wal_level": "logical"
    },
    "id": "runtime.42702-syntax-pg10.pg10",
    "observed": {
      "connection_autocommit": true,
      "diagnostic": {
        "column_name": null,
        "constraint_name": null,
        "context": null,
        "datatype_name": null,
        "exception_type": "AmbiguousColumn",
        "internal_position": null,
        "internal_query": null,
        "message_detail": null,
        "message_hint": null,
        "message_primary": "column reference \"id\" is ambiguous",
        "schema_name": null,
        "severity": "ERROR",
        "severity_nonlocalized": "ERROR",
        "source_file": "parse_relation.c",
        "source_function": "colNameToVar",
        "source_line": "791",
        "sqlstate": "42702",
        "statement_position": "8",
        "table_name": null,
        "text": "column reference \"id\" is ambiguous\nLINE 1: SELECT id FROM \"c42702_ambiguous_column\".\"left_table\", \"c427...\n               ^"
      },
      "failed_status": "IDLE",
      "repair_status": "IDLE",
      "repair_value": 1
    },
    "raw": "verify/results/42702-syntax-pg10/pg10/raw.jsonl",
    "raw_sha256": "365d4cc4c578a87ba6584daf52957335434f92cf584bf8711a9346d4a5199008",
    "run_id": "42702-syntax-pg10",
    "server_version": "10.21 (Debian 10.21-1.pgdg90+1)",
    "server_version_num": 100021,
    "snippet_registry": {
      "id": "snippet-registry.42702",
      "kind": "local_artifact",
      "path": "verify/cases/42702/snippets.json",
      "sha256": "b8d1edca0e090bda71ee447d0750e13f460c603a479818170bdfea34716bdf17",
      "source_role": "snippet_registry"
    },
    "status": "passed",
    "summary": "verify/results/42702-syntax-pg10/pg10/summary.json",
    "summary_sha256": "7dd5ef10f868a10985e0b82ad33629f8af8ba11be2824f2e98b59da55cfe669e",
    "target": "pg10"
  },
  "run_id": "42702-syntax-pg10",
  "runtime_id": "runtime.42702-syntax-pg10.pg10",
  "server_version": "10.21 (Debian 10.21-1.pgdg90+1)",
  "status": "passed",
  "target": "pg10"
}

sources · src.errcodes.18.6

{
  "commit": "724edf9bde9d356724ad384a2e196edc3c9f80f7",
  "docs_url": "",
  "kind": "upstream_source",
  "location": "",
  "path": "src/backend/utils/errcodes.txt",
  "position": 0,
  "sha256": "6e8de346643ba84aa3c9c6a73360acfc7b2dfb89162c06c08ce9bf5bcd5bbcba",
  "source_id": "src.errcodes.18.6",
  "tag": "REL_18_6",
  "url": "https://github.com/postgres/postgres/blob/724edf9bde9d356724ad384a2e196edc3c9f80f7/src/backend/utils/errcodes.txt"
}

sources · src.calls.REL_18_6

{
  "commit": "",
  "docs_url": "",
  "kind": "local_artifact",
  "location": "",
  "path": "raw/calls/REL_18_6.jsonl",
  "position": 1,
  "sha256": "9ee8a0e81d8f0825c5c1ae45583439859a26e602bdd4ce2f2a62aa278867ccbf",
  "source_id": "src.calls.REL_18_6",
  "tag": "",
  "url": ""
}

sources · src.calls.REL_10_23

{
  "commit": "",
  "docs_url": "",
  "kind": "local_artifact",
  "location": "",
  "path": "raw/calls/REL_10_23.jsonl",
  "position": 2,
  "sha256": "00d16d3eb01b71ccf1b245c8f3102f9d0ec9f36fb02777b8dd1b99fcb263040c",
  "source_id": "src.calls.REL_10_23",
  "tag": "",
  "url": ""
}

sources · src.ambiguous-column.18.6

{
  "commit": "724edf9bde9d356724ad384a2e196edc3c9f80f7",
  "docs_url": "",
  "kind": "upstream_source",
  "location": "",
  "path": "src/backend/parser/parse_relation.c",
  "position": 3,
  "sha256": "0d9c88f4a8def4c2d982c33f13208590e21ecf5e6f8cd9d7faa223dc771c9a9a",
  "source_id": "src.ambiguous-column.18.6",
  "tag": "REL_18_6",
  "url": "https://github.com/postgres/postgres/blob/724edf9bde9d356724ad384a2e196edc3c9f80f7/src/backend/parser/parse_relation.c#L960-L964"
}

sources · src.ambiguous-column.10.23

{
  "commit": "02991e79f8f58bc208f05dcc8af0c62dbe0a6ea4",
  "docs_url": "",
  "kind": "upstream_source",
  "location": "",
  "path": "src/backend/parser/parse_relation.c",
  "position": 4,
  "sha256": "a34f40fc93fa5df0015fe5af5ee7761ccba2d16a791cda69ae07848ed27616b5",
  "source_id": "src.ambiguous-column.10.23",
  "tag": "REL_10_23",
  "url": "https://github.com/postgres/postgres/blob/02991e79f8f58bc208f05dcc8af0c62dbe0a6ea4/src/backend/parser/parse_relation.c#L787-L791"
}

sources · manifest.42702

{
  "commit": "",
  "docs_url": "",
  "kind": "local_artifact",
  "location": "",
  "path": "verify/cases/42702/cases.json",
  "position": 5,
  "sha256": "31c6d96bb62ae0e507e1a627429d53825a5ecf30942b6df342a6ec68aadec3de",
  "source_id": "manifest.42702",
  "tag": "",
  "url": ""
}

sources · snippet-registry.42702

{
  "commit": "",
  "docs_url": "",
  "kind": "local_artifact",
  "location": "",
  "path": "verify/cases/42702/snippets.json",
  "position": 6,
  "sha256": "b8d1edca0e090bda71ee447d0750e13f460c603a479818170bdfea34716bdf17",
  "source_id": "snippet-registry.42702",
  "tag": "",
  "url": ""
}

来源引用

原始手册引用

完整定义与证据 JSON

定义来源

center · PostgreSQL 18 · english-manuals:a98b4dbb37246db878a9a1303cea5d3466fc55e929de197920c532e31442a64d

正文语言: zh-Hans · english-manuals:a98b4dbb37246db878a9a1303cea5d3466fc55e929de197920c532e31442a64d