diff --git a/work常用/数据库/Postgresql 常用SQL.md b/work常用/数据库/Postgresql 常用SQL.md
index 5628c57..1924ca4 100644
--- a/work常用/数据库/Postgresql 常用SQL.md	
+++ b/work常用/数据库/Postgresql 常用SQL.md	
@@ -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')
+```