注意的地方：拼接的sql可能超出了要截取的長度，字符串varchar2最多存儲4000
select to_char(substr(table_prefix || col_strs || table_subfix, 1, 4000)) con
from (select n.table_prefix,
wm_concat(m.col_str) as col_strs,
n.table_subfix
from (select a.table_name,
'drop table if exists ' || lower(a.table_name) ||
';create table ' || lower(a.table_name) || '(' as table_prefix,
') comment ''' || b.comments ||
''' ROW FORMAT DELIMITED FIELDS TERMINATED BY ''\t'' ESCAPED BY ''\\'' STORED AS TEXTFILE;' as table_subfix
from user_tables a, user_tab_comments b
where a.table_name = b.table_name
--and a.table_name = 'MID'
order by a.table_name) n,
(select c.TABLE_NAME,
c.column_name || ' ' ||
decode(c.data_type,
'VARCHAR2',
'varchar' || '(' || c.DATA_LENGTH || ')',
'NUMBER',
'int',
'DATE',
'timestamp',
'CHAR',
'CHAR' || '(' || c.DATA_LENGTH || ')',
'CLOB',
'string',
c.data_type) as col_str
from user_tab_cols c) m
where n.table_name = m.table_name
group by n.table_prefix, n.table_subfix)
union all
select 'alter table ' || c.TABLE_NAME || ' change ' || c.column_name || ' ' ||
c.column_name || ' ' || decode(c.data_type,
'VARCHAR2',
'varchar' || '(' || c.DATA_LENGTH || ')',
'NUMBER',
'int',
'DATE',
'timestamp',
'CHAR',
'CHAR' || '(' || c.DATA_LENGTH || ')',
'CLOB',
'string',
c.data_type) || ' comment ''' ||
d.comments || ''';' as col_str
from user_tab_cols c
left join user_col_comments d
on c.TABLE_NAME = d.table_name
and c.COLUMN_NAME = d.column_name下面的過程要注意plsql dev的緩衝問題declare
v_table_str varchar2(4000);
v_col_str varchar2(4000);
v_col_comments_str varchar2(4000);
v_type_str varchar2(50) := '';
begin
for v_temp in (select a.table_name, b.comments
from user_tables a, user_tab_comments b
where a.table_name = b.table_name
--and a.table_name = 'MID'
order by a.table_name) loop
v_table_str := 'create table ' || lower(v_temp.table_name) || '(';
for v_col in (select c.COLUMN_NAME,
c.DATA_TYPE,
c.DATA_LENGTH,
d.comments
from user_tab_cols c
WHERE c.TABLE_NAME = v_temp.table_name) loop
if v_col.data_type = 'VARCHAR2' then
v_type_str := 'VARCHAR(' || v_col.data_length || ')';
elsif v_col.data_type = 'NUMBER' then
v_type_str := 'int';
elsif v_col.data_type = 'DATE' then
v_type_str := 'timestamp';
elsif v_col.data_type = 'CHAR' then
v_type_str := 'CHAR(' || v_col.data_length || ')';
elsif v_col.data_type = 'CLOB' then
v_type_str := 'STRING';
else
v_type_str := v_col.data_type;
end if;
v_col_str := v_col_str || v_col.column_name || ' ' || v_col.data_type || ',';
end loop;
v_col_str := substr(v_col_str, 0, length(v_col_str) - 1);
v_table_str := v_table_str || v_col_str || ') comment ''' ||
v_temp.comments ||
''' ROW FORMAT DELIMITED FIELDS TERMINATED BY ''\t'' ESCAPED BY ''\\'' STORED AS TEXTFILE;';
dbms_output.put_line(v_table_str); --注意字符串長度過長
for v_col_comments in (select 'alter table ' || c.TABLE_NAME ||
' change ' || c.column_name || ' ' ||
c.column_name || ' ' ||
decode(c.data_type,
'VARCHAR2',
'varchar' || '(' || c.DATA_LENGTH || ')',
'NUMBER',
'int',
'DATE',
'timestamp',
'CHAR',
'CHAR' || '(' || c.DATA_LENGTH || ')',
'CLOB',
'string',
c.data_type) || ' comment ''' ||
d.comments || ''';' as col_comments
from user_tab_cols c
left join user_col_comments d
on c.TABLE_NAME = d.table_name
and c.COLUMN_NAME = d.column_name
WHERE c.TABLE_NAME = v_temp.table_name) loop
dbms_output.put_line(v_col_comments.col_comments);
end loop;
end loop;
end;
begin
for v_tmp in (select a.table_name,
'drop table if exists ' || lower(a.table_name) ||
';create table ' || lower(a.table_name) || '(' as table_prefix,
') comment ''' || b.comments ||
''' ROW FORMAT DELIMITED FIELDS TERMINATED BY ''~'' ESCAPED BY ''\\'' STORED AS TEXTFILE;' as table_subfix
from user_tables a, user_tab_comments b
where a.table_name = b.table_name) loop
insert into test_ww
(name)
select v_tmp.table_prefix || wm_concat(col_str) || v_tmp.table_subfix as col_strs
from (select c.TABLE_NAME,
c.column_name || ' ' ||
decode(c.data_type,
'VARCHAR2',
'varchar' || '(' || c.DATA_LENGTH || ')',
'NUMBER',
'int',
'DATE',
'timestamp',
'CHAR',
'CHAR' || '(' || c.DATA_LENGTH || ')',
'CLOB',
'string',
c.data_type) as col_str
from user_tab_cols c
where c.TABLE_NAME = v_tmp.table_name
order by c.COLUMN_ID);
commit;
end loop;
end;總結：第三種能原封不動的將表結構轉換(最重要的是字段的先後順序)