Question

我正在尝试将brs.parts表中的列从字符变为boolean更新。到目前为止，该列的数据为Y / N. 我正在使用以下命令

ALTER TABLE brs.parts ALTER COLUMN is_dpm_scanned TYPE BOOLEAN USING is_dpm_scanned::BOOLEAN

但是我收到以下错误：

*********错误**********

ERROR: default for column "is_dpm_scanned" cannot be cast automatically to type boolean
SQL state: 42804

表格定义是：

CREATE TABLE brs.parts (
    id serial NOT NULL PRIMARY KEY,
    webcrt_part_id INTEGER,
    event_id INTEGER,
    webcrt_job_id INTEGER,
    incoming_serial_number CHARACTER VARYING(256),
    outgoing_serial_number CHARACTER VARYING(256), 
    part_number CHARACTER VARYING(256),
    tag_number NUMERIC,
    is_dpm_scanned CHARACTER VARYING(1) DEFAULT 'N'::CHARACTER VARYING,
    current_operation_id INTEGER,
    creation_date DATE,
    created_by CHARACTER VARYING(20) NOT NULL,
    last_updated_date DATE,
    last_updated_by CHARACTER VARYING(20) NOT NULL,
    is_delete CHARACTER VARYING(1) DEFAULT 'N'::CHARACTER VARYING
);

Answer 1

在更改类型之前，您必须删除默认约束：

ALTER TABLE parts 
    ALTER COLUMN is_dpm_scanned DROP DEFAULT,
    ALTER COLUMN is_dpm_scanned TYPE BOOLEAN USING is_dpm_scanned::BOOLEAN,
    ALTER COLUMN is_dpm_scanned SET DEFAULT FALSE;

另请参阅：Changing a column from string to string array in postgresql。

Answer 2

如果将整数列转换为布尔值，则需要明确指定将哪些值视为true和什么是false。通常，0映射到false，其他所有映射到true。为此，请执行：

ALTER TABLE mytable ALTER mycolumn TYPE bool USING 
  CASE WHEN mycolumn=0 THEN FALSE 
  ELSE TRUE 
END;

列＆＃34; xxxx＆＃34;的默认值不能自动转换为在Postgres DB中键入boolean

2 个答案: