在 Python 中将自动增量主键添加到 PostgreSQL table

Question

我正在尝试将自动增量主键添加到从 pandas 数据框转换而来的 sql table。

将数据帧转换为sql并添加alter table命令以添加自动增量主键的代码如下

    test.to_sql('test_sql',schema='test_schema',con=conn,if_exists='replace',index=False)

with conn:
    conn.execute("ALTER TABLE test_schema.test_sql ADD XPK_test_sql id SERIAL PRIMARY KEY;")

我收到以下错误：

ProgrammingError: (psycopg2.errors.SyntaxError) syntax error at or near "SERIAL"

我检查了语法，似乎是正确的。我哪里错了？还有其他方法吗？

Answer 1

我不太确定您要做什么：该列是否已经存在并且您想将其设为主键，还是要创建一个新的主键列？

将主键约束添加到现有列

这些是 the docs 创建约束的语法：

ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
    action [, ... ]

...

where action is one of:

    ...
    ADD table_constraint [ NOT VALID ]
    ...


and table_constraint is:


[ CONSTRAINT constraint_name ]
{ CHECK ( expression ) [ NO INHERIT ] |
  UNIQUE ( column_name [, ... ] ) index_parameters |
  PRIMARY KEY ( column_name [, ... ] ) index_parameters |
  EXCLUDE [ USING index_method ] ( exclude_element WITH operator [, ... ] ) index_parameters [ WHERE ( predicate ) ] |
  FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ]
    [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE referential_action ] [ ON UPDATE referential_action ] }
[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

...


index_parameters in UNIQUE, PRIMARY KEY, and EXCLUDE constraints are:

[ INCLUDE ( column_name [, ... ] ) ]
[ WITH ( storage_parameter [= value] [, ... ] ) ]
[ USING INDEX TABLESPACE tablespace_name ]

所以你需要这样写

ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column_name)

添加 table table_name 的（现有）列 column_name 作为主键，新约束命名为 constraint_name.

添加新的主键列

文档是 on the same page:

ADD COLUMN [ IF NOT EXISTS ]

    This form adds a new column to the table, using the same syntax as CREATE TABLE.

CREATE TABLE docs IMO 的可读性不是很好，但这里是相关部分：

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name ( [
  { column_name data_type [ COMPRESSION compression_method ] [ COLLATE collation ] [ column_constraint [ ... ] ]
    | table_constraint
    | LIKE source_table [ like_option ... ] }
    [, ... ]
] )
...
where column_constraint is:
  ...
  PRIMARY KEY index_parameters 
  ...

index_parameters in UNIQUE, PRIMARY KEY, and EXCLUDE constraints are:


[ INCLUDE ( column_name [, ... ] ) ]
[ WITH ( storage_parameter [= value] [, ... ] ) ]
[ USING INDEX TABLESPACE tablespace_name ]
...

所以，这是您要查找的语法：

ALTER TABLE table_name ADD COLUMN column_name serial PRIMARY KEY

在 Python 中将自动增量主键添加到 PostgreSQL table

Add Autoincrement primary key to PostgreSQL table in Python

python

postgresql

sqlalchemy

psycopg2

pandas

将主键约束添加到现有列

添加新的主键列