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old-tom 7 months ago
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work常用/数据库/Postgresql 常用SQL.md
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@ -230,3 +230,197 @@ NULLIF(regexp_replace(po_number, '\D','','g'), '')::numeric
## 五、常见问题
## 六、常用函数
+ 生成建表语句
```sql
CREATE OR REPLACE FUNCTION show_create_table(
in_schema_name varchar,
in_table_name varchar
)
RETURNS text
LANGUAGE plpgsql VOLATILE
AS
$$
DECLARE
-- the ddl we're building
v_table_ddl text;
-- data about the target table
v_table_oid int;
v_table_type char;
v_partition_key varchar;
v_table_comment varchar;
-- records for looping
v_column_record record;
v_constraint_record record;
v_index_record record;
v_column_comment_record record;
v_index_comment_record record;
v_constraint_comment_record record;
BEGIN
-- grab the oid of the table; https://www.postgresql.org/docs/8.3/catalog-pg-class.html
SELECT c.oid, c.relkind INTO v_table_oid, v_table_type
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('r', 'p')
AND c.relname = in_table_name -- the table name
AND n.nspname = in_schema_name; -- the schema
-- throw an error if table was not found IF (v_table_oid IS NULL) THEN
RAISE EXCEPTION 'table does not exist';
END IF;
-- start the create definition
v_table_ddl := 'CREATE TABLE "' || in_table_name || '" (' || E'\n';
-- define all of the columns in the table; https://stackoverflow.com/a/8153081/3068233
FOR v_column_record IN
SELECT c.column_name,
c.data_type,
c.character_maximum_length,
c.is_nullable,
c.column_default
FROM information_schema.columns c
WHERE (table_schema, table_name) = (in_schema_name, in_table_name)
ORDER BY ordinal_position
LOOP
v_table_ddl := v_table_ddl || ' ' -- note: two char spacer to start, to indent the column
|| '"' || v_column_record.column_name || '" '
|| v_column_record.data_type || CASE WHEN v_column_record.character_maximum_length IS NOT NULL THEN ('(' || v_column_record.character_maximum_length || ')') ELSE '' END || ' '
|| CASE WHEN v_column_record.is_nullable = 'NO' THEN 'NOT NULL' ELSE 'NULL' END
|| CASE WHEN v_column_record.column_default IS NOT null THEN (' DEFAULT ' || v_column_record.column_default) ELSE '' END
|| ',' || E'\n';
END LOOP;
-- define all the constraints in the; https://www.postgresql.org/docs/9.1/catalog-pg-constraint.html && https://dba.stackexchange.com/a/214877/75296
FOR v_constraint_record IN
SELECT con.conname as constraint_name,
con.contype as constraint_type,
CASE
WHEN con.contype = 'p' THEN 1 -- primary key constraint
WHEN con.contype = 'u' THEN 2 -- unique constraint
WHEN con.contype = 'f' THEN 3 -- foreign key constraint
WHEN con.contype = 'c' THEN 4
ELSE 5
END as type_rank,
pg_get_constraintdef(con.oid) as constraint_definition
FROM pg_catalog.pg_constraint con
JOIN pg_catalog.pg_class rel ON rel.oid = con.conrelid
JOIN pg_catalog.pg_namespace nsp ON nsp.oid = connamespace
WHERE nsp.nspname = in_schema_name
AND rel.relname = in_table_name
ORDER BY type_rank
LOOP
IF v_constraint_record.constraint_type = 'p' THEN
v_table_ddl := v_table_ddl || ' '
|| v_constraint_record.constraint_definition
|| ',' || E'\n';
ELSE
v_table_ddl := v_table_ddl || ' ' -- note: two char spacer to start, to indent the column
|| 'CONSTRAINT' || ' '
|| '"' || v_constraint_record.constraint_name || '" '
|| v_constraint_record.constraint_definition
|| ',' || E'\n';
END IF;
END LOOP;
-- drop the last comma before ending the create statement
v_table_ddl = substr(v_table_ddl, 0, length(v_table_ddl) - 1) || E'\n';
-- end the create definition
v_table_ddl := v_table_ddl || ')';
IF v_table_type = 'p' THEN
SELECT pg_get_partkeydef(v_table_oid) INTO v_partition_key;
IF v_partition_key IS NOT NULL THEN
v_table_ddl := v_table_ddl || ' PARTITION BY ' || v_partition_key;
END IF;
END IF;
v_table_ddl := v_table_ddl || ';' || E'\n';
-- suffix create statement with all of the indexes on the table
FOR v_index_record IN
SELECT regexp_replace(indexdef, ' "?' || schemaname || '"?\.', ' ') AS indexdef
FROM pg_catalog.pg_indexes
WHERE (schemaname, tablename) = (in_schema_name, in_table_name)
AND indexname NOT IN (
select con.conname
FROM pg_catalog.pg_constraint con
JOIN pg_catalog.pg_class rel ON rel.oid = con.conrelid
JOIN pg_catalog.pg_namespace nsp ON nsp.oid = connamespace
WHERE nsp.nspname = in_schema_name
AND rel.relname = in_table_name
)
LOOP
v_table_ddl := v_table_ddl
|| v_index_record.indexdef
|| ';' || E'\n';
END LOOP;
-- comment on table
SELECT description INTO v_table_comment
FROM pg_catalog.pg_description
WHERE objoid = v_table_oid AND objsubid = 0;
IF v_table_comment IS NOT NULL THEN
v_table_ddl := v_table_ddl || 'COMMENT ON TABLE "' || in_table_name || '" IS ''' || replace(v_table_comment, '''', '''''') || ''';' || E'\n';
END IF;
-- comment on column
FOR v_column_comment_record IN
SELECT col.column_name, d.description
FROM information_schema.columns col
JOIN pg_catalog.pg_class c ON c.relname = col.table_name
JOIN pg_catalog.pg_namespace nsp ON nsp.oid = c.relnamespace AND col.table_schema = nsp.nspname
JOIN pg_catalog.pg_description d ON d.objoid = c.oid AND d.objsubid = col.ordinal_position
WHERE c.oid = v_table_oid
ORDER BY col.ordinal_position
LOOP
v_table_ddl := v_table_ddl || 'COMMENT ON COLUMN "' || in_table_name || '"."'
|| v_column_comment_record.column_name || '" IS '''
|| replace(v_column_comment_record.description, '''', '''''') || ''';' || E'\n';
END LOOP;
-- comment on index
FOR v_index_comment_record IN
SELECT c.relname, d.description
FROM pg_catalog.pg_index idx
JOIN pg_catalog.pg_class c ON idx.indexrelid = c.oid
JOIN pg_catalog.pg_description d ON idx.indexrelid = d.objoid
WHERE idx.indrelid = v_table_oid
LOOP
v_table_ddl := v_table_ddl || 'COMMENT ON INDEX "'
|| v_index_comment_record.relname || '" IS '''
|| replace(v_index_comment_record.description, '''', '''''') || ''';' || E'\n';
END LOOP;
-- comment on constraint
FOR v_constraint_comment_record IN
SELECT con.conname,
pg_description.description
FROM pg_catalog.pg_constraint con
JOIN pg_catalog.pg_class rel ON rel.oid = con.conrelid
JOIN pg_catalog.pg_namespace nsp ON nsp.oid = connamespace
JOIN pg_catalog.pg_description ON pg_description.objoid = con.oid
WHERE rel.oid = v_table_oid
LOOP
v_table_ddl := v_table_ddl || 'COMMENT ON CONSTRAINT "'
|| v_constraint_comment_record.conname || '" ON "' || in_table_name || '" IS '''
|| replace(v_constraint_comment_record.description, '''', '''''') || ''';' || E'\n';
END LOOP;
-- return the ddl
RETURN v_table_ddl;
END
$$;
```
```sql
-- 需要指定schema
select show_create_table('public', 'device')
```

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