我们从Python开源项目中，提取了以下38个代码示例，用于说明如何使用sqlalchemy.schema.DropConstraint()。
def drop_all_tables(engine, inspector, schema=None, include_names=None): from sqlalchemy import Column, Table, Integer, MetaData, \ ForeignKeyConstraint from sqlalchemy.schema import DropTable, DropConstraint if include_names is not None: include_names = set(include_names) with engine.connect() as conn: for tname, fkcs in reversed( inspector.get_sorted_table_and_fkc_names(schema=schema)): if tname: if include_names is not None and tname not in include_names: continue conn.execute(DropTable( Table(tname, MetaData(), schema=schema) )) elif fkcs: if not engine.dialect.supports_alter: continue for tname, fkc in fkcs: if include_names is not None and \ tname not in include_names: continue tb = Table( tname, MetaData(), Column('x', Integer), Column('y', Integer), schema=schema ) conn.execute(DropConstraint( ForeignKeyConstraint( [tb.c.x], [tb.c.y], name=fkc) ))
def drop_constraint(self, const): self._exec(schema.DropConstraint(const))
def _visit_constraint(self, constraint): constraint.name = self.get_constraint_name(constraint) self.append(self.process(DropConstraint(constraint, cascade=constraint.cascade))) self.execute()
def drop_all_tables(engine, inspector, schema=None, include_names=None): from sqlalchemy import Column, Table, Integer, MetaData, \ ForeignKeyConstraint from sqlalchemy.schema import DropTable, DropConstraint if include_names is not None: include_names = set(include_names) with engine.connect() as conn: for tname, fkcs in reversed( inspector.get_sorted_table_and_fkc_names(schema=schema)): if tname: if include_names is not None and tname not in include_names: continue conn.execute(DropTable( Table(tname, MetaData()) )) elif fkcs: if not engine.dialect.supports_alter: continue for tname, fkc in fkcs: if include_names is not None and \ tname not in include_names: continue tb = Table( tname, MetaData(), Column('x', Integer), Column('y', Integer), schema=schema ) conn.execute(DropConstraint( ForeignKeyConstraint( [tb.c.x], [tb.c.y], name=fkc) ))
def drop_everything(echo=True): """ Pre-gather all named constraints and table names, and drop everything. This is better than using metadata.reflect(); metadata.drop_all() as it handles cyclical constraints between tables. Ref. http://www.sqlalchemy.org/trac/wiki/UsageRecipes/DropEverything """ engine = session.get_engine(echo=echo) conn = engine.connect() # the transaction only applies if the DB supports # transactional DDL, i.e. Postgresql, MS SQL Server trans = conn.begin() inspector = reflection.Inspector.from_engine(engine) # gather all data first before dropping anything. # some DBs lock after things have been dropped in # a transaction. metadata = MetaData() tbs = [] all_fks = [] for table_name in inspector.get_table_names(): fks = [] for fk in inspector.get_foreign_keys(table_name): if not fk['name']: continue fks.append(ForeignKeyConstraint((), (), name=fk['name'])) t = Table(table_name, metadata, *fks) tbs.append(t) all_fks.extend(fks) for fkc in all_fks: try: print str(DropConstraint(fkc)) + ';' conn.execute(DropConstraint(fkc)) except: print format_exc() for table in tbs: try: print str(DropTable(table)).strip() + ';' conn.execute(DropTable(table)) except: print format_exc() trans.commit()
