pg没有提供生成创建字段的函数，需要自己查表实现。其他包括约束、索引等都有系统函数，在其基础上加工使用即可。
支持生成包含：字段（支持数组类型字段）、约束、索引（支持生成唯一索引，支持全类型索引）在内的建表语句。
生成的sql指定scheme为：【sch_租户id】，不同scheme生成规则或者不需要指定scheme直接修改下相关代码即可使用。代码如下：
1 CREATE OR REPLACE FUNCTION "public"."showcreatetable"("dbinstancename" varchar, "namespace" varchar, "tablename" varchar, "tenantid" varchar) 2 RETURNS "pg_catalog"."varchar" AS $BODY$ 3 declare 4 tableScript character varying default ''; 5 indexScripe character varying default ''; 6 constraintScripe character varying default ''; 7 p_namespace character varying default ''; 8 p_tablename character varying default ''; 9 tableNum int2 ; 10 constraintIds oid[]; 11 v_conname varchar; 12 13 begin 14 p_namespace := namespace; 15 p_tablename := tablename; 16 -- check db extist 17 tableNum := count(*) 18 from pg_class 19 where relname = p_tablename 20 and relnamespace = ( 21 select oid 22 from pg_namespace 23 where nspname = p_namespace 24 ); 25 IF tableNum = 0 then 26 return '' ; 27 end if; 28 -- columns 29 tableScript := tableScript || ' CREATE TABLE IF NOT EXISTS ' || '"sch_' || tenantid || '".' || p_tablename || ' ( ' || array_to_string( 30 array( 31 select concat(c1, c2, c3, c4, c5, c6) as column_line 32 from ( 33 select '"' || column_name || '"' || ' ' || 34 case 35 when data_type = 'ARRAY' then ltrim(udt_name, '_') || '[]' 36 when data_type = 'USER-DEFINED' then udt_name 37 else data_type end as c1, 38 case when character_maximum_length > 0 then '(' || character_maximum_length || ')' end as c2, 39 case when numeric_precision > 0 and numeric_scale < 1 then null end as c3, 40 case when numeric_precision > 0 and numeric_scale > 0 then null end as c4, 41 case when is_nullable = 'NO' then ' NOT NULL' end as c5, 42 case when column_default is not Null then ' DEFAULT' end || ' ' || replace(case 43 when position('nextval(''"' in column_default) > 0 44 then replace(column_default, 'nextval(''"', 'nextval(''"' || 'sch_' || tenantid || '.') 45 when 46 position('nextval(''' in column_default) > 0 47 then 48 replace(column_default, 'nextval(''', 'nextval(''' || 'sch_' || tenantid || '.') 49 ELSE column_default 50 end, '::character varying', '') as c6 51 from information_schema.columns 52 where table_name = p_tablename 53 and table_catalog = dbinstancename 54 and table_schema = p_namespace 55 order by ordinal_position 56 ) as string_columns 57 ), ' , ') || ','; 58 59 60 -- 约束 61 constraintIds := array(select oid 62 from pg_constraint c 63 where conrelid = ( 64 select oid 65 from pg_class 66 where relname = p_tablename 67 and relnamespace = ( 68 select oid 69 from pg_namespace 70 where nspname = p_namespace 71 ) 72 )); 73 74 if array_length(constraintIds, 1) > 0 then 75 for i in 1..array_length(constraintIds, 1) 76 loop 77 v_conname := conname 78 from pg_constraint c 79 where c.oid = constraintIds[i]; 80 constraintScripe := constraintScripe || ' CONSTRAINT ' 81 '"' || v_conname || '"' || pg_get_constraintdef(constraintIds[i]) || ','; 82 end loop; 83 constraintScripe := rtrim(constraintScripe, ','); 84 end if; 85 86 if constraintScripe = '' or constraintScripe is null then 87 tableScript := trim(trailing ',' from tableScript); 88 end if; 89 tableScript := tableScript || constraintScripe || ' ); '; 90 91 /** **/ 92 --- 获取非约束索引 column 93 indexScripe := array_to_string(ARRAY(SELECT CASE 94 WHEN position('"' in indexdef) > 0 THEN 95 replace(indexdef,' INDEX ',' INDEX IF NOT EXISTS ') 96 ELSE 97 replace(replace(indexdef,' INDEX ',' INDEX IF NOT EXISTS '), indexname, '"' || indexname || '"') 98 END 99 from pg_indexes i 100 where i.schemaname = p_namespace 101 and i.tablename = p_tablename 102 and i.indexname not in 103 (select distinct conname 104 from pg_constraint c 105 where conrelid = ( 106 select oid 107 from pg_class 108 where relname = p_tablename 109 and relnamespace = ( 110 select oid 111 from pg_namespace 112 where nspname = p_namespace 113 ) 114 ))), ';'); 115 116 if indexScripe <> '' or indexScripe is not null then 117 indexScripe := replace(indexScripe, ' ' || p_namespace || '.' || p_tablename || ' ', ' "sch_' || tenantid || '".' || p_tablename || ' ') || ';'; 118 tableScript := tableScript || indexScripe; 119 end if; 120 121 122 return tableScript; 123 124 end 125 $BODY$ 126 LANGUAGE plpgsql VOLATILE 127 COST 100