Summary: in this tutorial, you will learn about the PostgreSQL foreign key and how to add foreign keys to tables using foreign key constraints. Introduction to PostgreSQL Foreign Key Constraint In PostgreSQL, a foreign key is a column or a group of columns in a table that uniquely identifies ...
Every movie needs a director and every rented movie needs to exist in the store. How do we make sure something in another table exists before inserting new data? This lesson will teach us about foreign keys and references. CREATETABLEdirectors ( id SERIALPRIMARYKEY, nameVARCHAR(100)UNIQUENOTNU...
一、简介在数据库管理中，外键是一种重要的约束，用于确保数据的一致性和完整性。然而，在某些情况下，我们可能需要删除或修改外键。本文将介绍如何使用Python中的petl库将PostgreSQL中所有表的外键删除，迁移数据，并重新建立外键。二、安装petl和psycopg2首先，我们需要安装petl和psycopg2库。在命令行中输入以下命令进行...
for table in tables: # 从源数据库读取表的数据和外键信息 data = load(f"SELECT *, '{table}'::regclass::text AS table_name FROM {table}.\"%\";") foreign_keys = load(f"SELECT * FROM {table}_key;") # 删除外键并迁移数据到新表 for fk in foreign_keys: if fk[3] != 'PRIMARY'...
fortableintables:# 从源数据库读取表的数据和外键信息data=load(f"SELECT *, '{table}'::regclass::text AS table_name FROM{table}.\"%\";")foreign_keys=load(f"SELECT * FROM{table}_key;")# 删除外键并迁移数据到新表forfkinforeign_keys:iffk[3]!='PRIMARY':# 如果不是主键外键,才删除外键并...
fortableintables:# 从源数据库读取表的数据和外键信息data=load(f"SELECT *, '{table}'::regclass::text AS table_name FROM{table}.\"%\";")foreign_keys=load(f"SELECT * FROM{table}_key;")# 删除外键并迁移数据到新表forfkinforeign_keys:iffk[3]!='PRIMARY':# 如果不是主键外键,才删除外键并...
pt-osc提供--alter-foreign-keys-method选项来决定怎么处理这种情况: rebuild_constraints,优先采用这种方式 它先通过alter table t2 drop fk1,add _fk1重建外键参考,指向新表 再rename t1 t1_old, _t1_new t1,交换表名,不影响客户端 删除旧表 t1_old ...
data = load(f"SELECT *, '{table}'::regclass::text AS table_name FROM {table}.\"%\";") foreign_keys = load(f"SELECT * FROM {table}_key;") # 删除外键并迁移数据到新表 for fk in foreign_keys: if fk[3] != 'PRIMARY': # 如果不是主键外键,才删除外键并迁移数据到新表 cur.execut...
Primary keys, which must include the partition key column Foreign keys Check constraints References Creating indexes for the full table or each specific partition. You can't alter the schema for an individual partition. However, you can alter the parent table (such as adding a new column...
Azure Cosmos DB for PostgreSQL 不会取消分发具有外键或被外键引用的表,除非 cascade_via_foreign_keys 参数设置为 true。 如果此参数为 false(或省略),则必须在取消分发之前手动删除有问题的外键约束。 参数 table_name:要取消分发的已分发表或引用表的名称。