コンテンツ
1.アプリケーションの背景
データ移行は仕事でよく使用されます。特に、さまざまなタイプのデータベースでは、一貫性のないテーブル作成構文が使用されます。以下は、oracle関数を使用したMySQLテーブル作成DDLの出力です。
2.機能の実現
1.コード
create or replace function fn_crea_tab_oracle2mysql
( i_owner in string,
i_table_name in string,
i_number_default_type in string := 'decimal',
i_auto_incretment_column_name in string := 'ID' -- '%ID'
)
/*
功能：ORACLE表生成MYSQL建表DDL
参数说明：
i_owner:schema名
i_table_name:表名
i_number_default_type:NUMBER默认转换的类型，缺省是decimal
i_auto_incretment_column_name:自增属性字段名称规则，默认是ID，可传进来已知的自增字段
已知问题：
1.不支持分区
2.不支持函数索引，位图索引等特殊索引定义
3.不支持自定义数据类型，不支持ROWID,RAW等特殊数据类型
4.不支持外键
5.不支持自定义约束
6.不支持与空间、事务相关属性
7.DATE与TIMESTAMP转换成datetime，需注意精度
8.超大NUMBER直接转换为bigint，需注意精度
9.auto incretment 是根据字段名规则加一些判断，设置不一定准确，需检查
*/
return clob is
Result clob;
cnt number;
data_type varchar2(128);
column_str varchar2(4000);
table_comments varchar2(4000);
is_pk_column number := 0;
begin
select count(*) into cnt
from all_tables
where owner = upper(i_owner)
and table_name = upper(i_table_name);
if (cnt = 0) then
RAISE_APPLICATION_ERROR(-20000,'can not found table,please check input!');
else
Result := 'CREATE TABLE `' || lower(i_table_name) || '`(';
/*
字段数据类型
*/
for c in (select a.column_name,
a.data_type,
a.data_length,
a.data_precision,
a.data_scale,
a.nullable,
a.data_default,
b.COMMENTS
from all_tab_cols a, all_col_comments b
where a.owner = upper(i_owner)
and a.table_name = upper(i_table_name)
and a.HIDDEN_COLUMN = 'NO'
and a.owner = b.OWNER
and a.TABLE_NAME = b.TABLE_NAME
and a.COLUMN_NAME = b.COLUMN_NAME
order by a.column_id) loop
if (c.data_type = 'VARCHAR2' or c.data_type = 'NVARCHAR2') then
data_type := 'varchar(' || c.data_length || ')';
elsif (c.data_type = 'CHAR' or c.data_type = 'NCHAR') then
data_type := 'char(' || c.data_length || ')';
elsif (c.data_type = 'NUMBER') then
if (c.data_precision is not null and (c.data_scale = 0 or c.data_scale is null) ) then
data_type := 'int(' || c.data_precision || ')';
elsif (c.data_precision is not null and c.data_scale is not null) then
data_type := 'decimal(' || c.data_precision || ',' || c.data_scale || ')';
else
data_type := i_number_default_type;
end if;
elsif (c.data_type = 'DATE' or c.data_type like 'TIMESTAMP%') then
data_type := 'datetime';
elsif (c.data_type = 'CLOB' or c.data_type = 'NCLOB' or
c.data_type = 'LONG') then
data_type := 'text';
elsif (c.data_type = 'BLOB' or c.data_type = 'LONG RAW') then
data_type := 'blob';
elsif (c.data_type = 'BINARY_FLOAT') then
data_type := 'float';
elsif (c.data_type = 'BINARY_DOUBLE') then
data_type := 'double';
else
data_type := c.data_type;
end if;
column_str := ' `' || lower(c.column_name) || '` ' || data_type;
/*
自增主键：id列视为自增id列
*/
if (c.column_name = upper(i_auto_incretment_column_name) and
(c.data_scale is null or c.data_scale = 0)) then
select count(*)
into is_pk_column
from all_constraints a, all_cons_columns b
where a.owner = upper(i_owner)
and a.table_name = upper(i_table_name)
and a.constraint_type = 'P'
and a.OWNER = b.OWNER
and a.TABLE_NAME = b.TABLE_NAME
and a.CONSTRAINT_NAME = b.CONSTRAINT_NAME
and b.COLUMN_NAME = c.column_name;
if is_pk_column > 0 then
column_str := column_str || ' AUTO_INCREMENT';
end if;
end if;
/*
字段是否可为空
*/
if c.nullable = 'N' then
column_str := column_str || ' NOT NULL';
end if;
if (trim(c.data_default) is not null) then
column_str := column_str || ' DEFAULT ' ||
trim(replace(replace(c.data_default, chr(13), ''),
chr(10),
''));
end if;
/*
字段注释
*/
if c.comments is not null then
column_str := column_str || ' COMMENT ''' || c.comments || '''';
end if;
/*
结果组装
*/
Result := Result || chr(10) || column_str || ',';
end loop;
/*
主键
*/
for c in (select a.constraint_name, wm_concat(a.column_name) pk_columns
from (select a.CONSTRAINT_NAME,
'`' || b.COLUMN_NAME || '`' column_name
from all_constraints a, all_cons_columns b
where a.owner = upper(i_owner)
and a.table_name = upper(i_table_name)
and a.constraint_type = 'P'
and a.OWNER = b.OWNER
and a.TABLE_NAME = b.TABLE_NAME
and a.CONSTRAINT_NAME = b.CONSTRAINT_NAME
order by b.POSITION) a
group by a.constraint_name) loop
Result := Result || chr(10) || ' PRIMARY KEY (' ||
lower(c.pk_columns) || '),';
end loop;
/*
唯一键
*/
for c in (select a.constraint_name, wm_concat(a.column_name) uk_columns
from (select a.CONSTRAINT_NAME,
'`' || b.COLUMN_NAME || '`' column_name
from all_constraints a, all_cons_columns b
where a.owner = upper(i_owner)
and a.table_name = upper(i_table_name)
and a.constraint_type = 'U'
and a.OWNER = b.OWNER
and a.TABLE_NAME = b.TABLE_NAME
and a.CONSTRAINT_NAME = b.CONSTRAINT_NAME
order by b.POSITION) a
group by a.constraint_name) loop
Result := Result || chr(10) || ' UNIQUE KEY `' ||
lower(c.constraint_name) || '`(' || lower(c.uk_columns) || '),';
end loop;
/*
索引
*/
for c in (select a.index_name, wm_concat(a.column_name) ind_columns
from (select a.index_name,
'`' || a.COLUMN_NAME || '`' column_name
from all_ind_columns a
where a.table_owner = upper(i_owner)
and a.TABLE_NAME = upper(i_table_name)
and not exists
(select index_name
from all_constraints b
where a.TABLE_OWNER = b.owner
and a.TABLE_NAME = b.TABLE_NAME
and a.INDEX_NAME = b.INDEX_NAME)
order by a.COLUMN_POSITION) a
group by a.index_name) loop
Result := Result || chr(10) || ' KEY `' || lower(c.index_name) || '`(' ||
lower(c.ind_columns) || '),';
end loop;
Result := substr(Result, 1, length(result) - 1) || chr(10) || ')';
/*
表注释
*/
select max(a.COMMENTS)
into table_comments
from all_tab_comments a
where owner = upper(i_owner)
and table_name = upper(i_table_name);
if (table_comments is not null) then
Result := Result || 'COMMENT=''' || table_comments || '''';
end if;
Result := Result || ';';
end if;
return(Result);
end fn_crea_tab_oracle2mysql;
2.効果
