如果指定了 unique=True 的列，那么在插入数据的时候，如果值重复了，sqlite 就会报错，如果想忽略这个冲突，那么就可以使用下面的几个方法。

方法一：在定义 table 的时候指定 IGNORE

参考：https://docs.sqlalchemy.org/en/14/dialects/sqlite.html

联合住键

some_table = Table(
    'some_table', metadata,
    Column('id', Integer, primary_key=True),
    Column('data', Integer),
    UniqueConstraint('id', 'data', sqlite_on_conflict='IGNORE')
)

相当于如下SQL语句

CREATE TABLE some_table (
    id INTEGER NOT NULL,
    data INTEGER,
    PRIMARY KEY (id),
    UNIQUE (id, data) ON CONFLICT IGNORE
)

单键

some_table = Table(
    'some_table', metadata,
    Column('id', Integer, primary_key=True),
    Column('data', Integer, unique=True,
           sqlite_on_conflict_unique='IGNORE')
)

相当于如下SQL语句

CREATE TABLE some_table (
    id INTEGER NOT NULL,
    data INTEGER,
    PRIMARY KEY (id),
    UNIQUE (data) ON CONFLICT IGNORE
)

或者

class Config(Base):
    __tablename__ = "config"

    __table_args__ = (sqlalchemy.UniqueConstraint('schema','key', sqlite_on_conflict='IGNORE'),)
    id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True, autoincrement=True)
    schema = sqlalchemy.Column(sqlalchemy.String(128), default=None, nullable=True)
    key = sqlalchemy.Column(sqlalchemy.String(128), default=None, nullable=True)
    value = sqlalchemy.Column(sqlalchemy.String(512), nullable=False)

或者

class Urls(Base):
    __tablename__ = "urls"

    id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True, autoincrement=True)
    title = sqlalchemy.Column(sqlalchemy.String(512))
    url = sqlalchemy.Column(sqlalchemy.String(1024), nullable=False, unique=True, sqlite_on_conflict_unique='IGNORE')
    addtime = sqlalchemy.Column(sqlalchemy.DateTime(), default=datetime.datetime.now, nullable=False)

方法二：在执行 SQL 的时候指定 IGNORE

参考：https://stackoverflow.com/questions/2218304/sqlalchemy-insert-ignore

• prefix_with("OR REPLACE")

inserter = table_object.insert().prefix_with("OR REPLACE")
inserter.execute([{'column1':'value1'}, {'column1':'value2'}])

• use a compiler extension

from sqlalchemy.ext.compiler import compiles
from sqlalchemy.sql.expression import Insert
#
@compiles(Insert)
def _prefix_insert_with_ignore(insert, compiler, **kw):
    return compiler.visit_insert(insert.prefix_with('OR IGNORE'), **kw)

OR

from sqlalchemy.ext.compiler import compiles, deregister
from sqlalchemy.sql.expression import Insert
#
def _prefix_insert_with_ignore(insert, compiler, **kw):
    return compiler.visit_insert(insert.prefix_with('OR IGNORE'), **kw)
#
compiles(Insert)(_prefix_insert_with_replace)
try:
    # do some inserts...
finally:
    deregister(Insert)

方法三：在 sql 语句中使用 IGNORE

参考：https://stackoverflow.com/questions/35415469/sqlite3-unique-constraint-failed-error

INSERT or IGNORE into tablename VALUES (value1,value2 , so on );

或者

INSERT or REPLACE into tablename VALUES (value1,value2 , so on );