我已经在postgreSQL中创建了一个表。我想查看用于创建表的SQL语句,但无法找出它。

如何通过命令行或SQL语句获得Postgres中现有表的创建表SQL语句?


当前回答

(注意-此解决方案不适用于PostgreSQL v12+)


我的解决方案是使用psql和-E选项登录postgres db,如下所示:

psql -E -U username -d database   

在psql中,运行以下命令查看postgres用来生成的sql 描述表语句:

-- List all tables in the schema (my example schema name is public)
\dt public.*
-- Choose a table name from above
-- For create table of one public.tablename
\d+ public.tablename  

基于运行这些描述命令后返回的sql,我能够把它们放在一起 下面是PLPGSQL函数:

CREATE OR REPLACE FUNCTION generate_create_table_statement(p_table_name varchar)
  RETURNS text AS
$BODY$
DECLARE
    v_table_ddl   text;
    column_record record;
BEGIN
    FOR column_record IN 
        SELECT 
            b.nspname as schema_name,
            b.relname as table_name,
            a.attname as column_name,
            pg_catalog.format_type(a.atttypid, a.atttypmod) as column_type,
            CASE WHEN 
                (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)
                 FROM pg_catalog.pg_attrdef d
                 WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef) IS NOT NULL THEN
                'DEFAULT '|| (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)
                              FROM pg_catalog.pg_attrdef d
                              WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef)
            ELSE
                ''
            END as column_default_value,
            CASE WHEN a.attnotnull = true THEN 
                'NOT NULL'
            ELSE
                'NULL'
            END as column_not_null,
            a.attnum as attnum,
            e.max_attnum as max_attnum
        FROM 
            pg_catalog.pg_attribute a
            INNER JOIN 
             (SELECT c.oid,
                n.nspname,
                c.relname
              FROM pg_catalog.pg_class c
                   LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
              WHERE c.relname ~ ('^('||p_table_name||')$')
                AND pg_catalog.pg_table_is_visible(c.oid)
              ORDER BY 2, 3) b
            ON a.attrelid = b.oid
            INNER JOIN 
             (SELECT 
                  a.attrelid,
                  max(a.attnum) as max_attnum
              FROM pg_catalog.pg_attribute a
              WHERE a.attnum > 0 
                AND NOT a.attisdropped
              GROUP BY a.attrelid) e
            ON a.attrelid=e.attrelid
        WHERE a.attnum > 0 
          AND NOT a.attisdropped
        ORDER BY a.attnum
    LOOP
        IF column_record.attnum = 1 THEN
            v_table_ddl:='CREATE TABLE '||column_record.schema_name||'.'||column_record.table_name||' (';
        ELSE
            v_table_ddl:=v_table_ddl||',';
        END IF;

        IF column_record.attnum <= column_record.max_attnum THEN
            v_table_ddl:=v_table_ddl||chr(10)||
                     '    '||column_record.column_name||' '||column_record.column_type||' '||column_record.column_default_value||' '||column_record.column_not_null;
        END IF;
    END LOOP;

    v_table_ddl:=v_table_ddl||');';
    RETURN v_table_ddl;
END;
$BODY$
  LANGUAGE 'plpgsql' COST 100.0 SECURITY INVOKER;

下面是函数用法:

SELECT generate_create_table_statement('tablename');

下面是drop语句,如果你不想让这个函数永久保存:

DROP FUNCTION generate_create_table_statement(p_table_name varchar);

其他回答

如果您不想创建函数,而只想让查询创建一个基本的表结构,这里有一个解决方案。

select 'CREATE TABLE ' || table_name ||'(' ||STRING_AGG (
    column_name || ' ' || data_type ,
        ','
       ORDER BY
        table_name,
        ordinal_position
    ) ||');'
    from 
information_schema.columns 
where table_schema = 'public'
group by 
table_name

我能想到的最简单的方法是安装pgAdmin 3(在这里找到),并用它来查看数据库。它将自动生成一个查询,该查询将创建所讨论的表。

一个简单的解决方案,在纯SQL。 您可以将其扩展到您想要显示的更多属性。

with c as (
SELECT table_name, ordinal_position, 
 column_name|| ' ' || data_type col
, row_number() over (partition by table_name order by ordinal_position asc) rn
, count(*) over (partition by table_name) cnt
FROM information_schema.columns
WHERE table_name   in ('pg_index', 'pg_tables')
order by table_name, ordinal_position
)
select case when rn = 1 then 'create table ' || table_name || '(' else '' end
 || col 
 || case when rn < cnt then ',' else '); ' end
from c 
order by table_name, rn asc;

输出:

create table pg_index(indexrelid oid,
 indrelid oid,
 indnatts smallint,
 indisunique boolean,
 indisprimary boolean,
 indisexclusion boolean,
 indimmediate boolean,
 indisclustered boolean,
 indisvalid boolean,
 indcheckxmin boolean,
 indisready boolean,
 indislive boolean,
 indisreplident boolean,
 indkey ARRAY,
 indcollation ARRAY,
 indclass ARRAY,
 indoption ARRAY,
 indexprs pg_node_tree,
 indpred pg_node_tree);

 create table pg_tables(schemaname name,
 tablename name,
 tableowner name,
 tablespace name,
 hasindexes boolean,
 hasrules boolean,
 hastriggers boolean,
 rowsecurity boolean);

如果你想找到一个表的create语句而不使用pg_dump,这个查询可能对你有用(改变'tablename'与你的表被称为什么):

SELECT                                          
  'CREATE TABLE ' || relname || E'\n(\n' ||
  array_to_string(
    array_agg(
      '    ' || column_name || ' ' ||  type || ' '|| not_null
    )
    , E',\n'
  ) || E'\n);\n'
from
(
  SELECT 
    c.relname, a.attname AS column_name,
    pg_catalog.format_type(a.atttypid, a.atttypmod) as type,
    case 
      when a.attnotnull
    then 'NOT NULL' 
    else 'NULL' 
    END as not_null 
  FROM pg_class c,
   pg_attribute a,
   pg_type t
   WHERE c.relname = 'tablename'
   AND a.attnum > 0
   AND a.attrelid = c.oid
   AND a.atttypid = t.oid
 ORDER BY a.attnum
) as tabledefinition
group by relname;

当直接从psql调用时,这样做是有用的:

\pset linestyle old-ascii

另外,这个线程中的generate_create_table_statement函数工作得很好。

这是这个老问题的另一个解决方案。多年来,关于这个问题有许多优秀的答案,我的尝试在很大程度上借鉴了它们。

我使用安德烈·列别登科的解决方案作为起点,因为它的输出已经非常接近我的要求。

特点:

following common practice I have moved the foreign key constraints outside the table definition. They are now included as ALTER TABLE statements at the bottom. The reason is that a foreign key can also link to a column of the same table. In that fringe case the constraint can only be created after the table creation is completed. The create table statement would throw an error otherwise. The layout and indenting looks nicer now (at least to my eye) Drop command (commented out) in the header of the definition The solution is offered here as a plpgsql function. The algorithm does however not use any procedural language. The function just wraps one single query that can be used in a pure sql context as well. removed redundant subqueries Identifiers are now quoted if they are identical to reserved postgresql language elements replaced the string concatenation operator || with the appropriate string functions to improve performance, security and readability of the code. Note: the || operator produces NULL if one of the combined strings is NULL. It should only be used when that is the desired behaviour. (check out the usage in the code below for an example)


CREATE OR REPLACE FUNCTION public.wmv_get_table_definition (
    p_schema_name character varying,
    p_table_name character varying
)
    RETURNS SETOF TEXT
    AS $BODY$
BEGIN
    RETURN query 
    WITH table_rec AS (
        SELECT
            c.relname, n.nspname, c.oid
        FROM
            pg_catalog.pg_class c
            LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
        WHERE
            relkind = 'r'
            AND n.nspname = p_schema_name
            AND c.relname LIKE p_table_name
        ORDER BY
            c.relname
    ),
    col_rec AS (
        SELECT
            a.attname AS colname,
            pg_catalog.format_type(a.atttypid, a.atttypmod) AS coltype,
            a.attrelid AS oid,
            ' DEFAULT ' || (
                SELECT
                    pg_catalog.pg_get_expr(d.adbin, d.adrelid)
                FROM
                    pg_catalog.pg_attrdef d
                WHERE
                    d.adrelid = a.attrelid
                    AND d.adnum = a.attnum
                    AND a.atthasdef) AS column_default_value,
            CASE WHEN a.attnotnull = TRUE THEN
                'NOT NULL'
            ELSE
                'NULL'
            END AS column_not_null,
            a.attnum AS attnum
        FROM
            pg_catalog.pg_attribute a
        WHERE
            a.attnum > 0
            AND NOT a.attisdropped
        ORDER BY
            a.attnum
    ),
    con_rec AS (
        SELECT
            conrelid::regclass::text AS relname,
            n.nspname,
            conname,
            pg_get_constraintdef(c.oid) AS condef,
            contype,
            conrelid AS oid
        FROM
            pg_constraint c
            JOIN pg_namespace n ON n.oid = c.connamespace
    ),
    glue AS (
        SELECT
            format( E'-- %1$I.%2$I definition\n\n-- Drop table\n\n-- DROP TABLE IF EXISTS %1$I.%2$I\n\nCREATE TABLE %1$I.%2$I (\n', table_rec.nspname, table_rec.relname) AS top,
            format( E'\n);\n\n\n-- adempiere.wmv_ghgaudit foreign keys\n\n', table_rec.nspname, table_rec.relname) AS bottom,
            oid
        FROM
            table_rec
    ),
    cols AS (
        SELECT
            string_agg(format('    %I %s%s %s', colname, coltype, column_default_value, column_not_null), E',\n') AS lines,
            oid
        FROM
            col_rec
        GROUP BY
            oid
    ),
    constrnt AS (
        SELECT
            string_agg(format('    CONSTRAINT %s %s', con_rec.conname, con_rec.condef), E',\n') AS lines,
            oid
        FROM
            con_rec
        WHERE
            contype <> 'f'
        GROUP BY
            oid
    ),
    frnkey AS (
        SELECT
            string_agg(format('ALTER TABLE %I.%I ADD CONSTRAINT %s %s', nspname, relname, conname, condef), E';\n') AS lines,
            oid
        FROM
            con_rec
        WHERE
            contype = 'f'
        GROUP BY
            oid
    )
    SELECT
        concat(glue.top, cols.lines, E',\n', constrnt.lines, glue.bottom, frnkey.lines, ';')
    FROM
        glue
        JOIN cols ON cols.oid = glue.oid
        LEFT JOIN constrnt ON constrnt.oid = glue.oid
        LEFT JOIN frnkey ON frnkey.oid = glue.oid;
END;
$BODY$
LANGUAGE plpgsql;