获取某个数据库中所有表的信息的操作oracle和mysql的操作

<if test="dbName == 'oracle'">
SELECT
t.TABLE_NAME AS name,
c.COMMENTS AS comments
FROM user_tables t, user_tab_comments c
WHERE t.table_name = c.table_name
<if test="name != null and name != ''">
AND t.TABLE_NAME = upper(#{name})
</if>
ORDER BY t.TABLE_NAME
</if>

<if test="dbName == 'mysql'">
SELECT t.table_name AS name,t.TABLE_COMMENT AS comments
FROM information_schema.`TABLES` t
WHERE t.TABLE_SCHEMA = (select database())
<if test="name != null and name != ''">
AND t.TABLE_NAME = upper(#{name})
</if>
ORDER BY t.TABLE_NAME
</if>

<if test="dbName == 'oracle'">
SELECT
t.COLUMN_NAME AS name,
(CASE WHEN t.NULLABLE = 'Y' THEN '1' ELSE '0' END) AS isNull,
(t.COLUMN_ID * 10) AS sort,
c.COMMENTS AS comments,
decode(t.DATA_TYPE,'DATE',t.DATA_TYPE || '(' || t.DATA_LENGTH || ')',
'VARCHAR2', t.DATA_TYPE || '(' || t.DATA_LENGTH || ')',
'VARCHAR', t.DATA_TYPE || '(' || t.DATA_LENGTH || ')',
'NVARCHAR2', t.DATA_TYPE || '(' || t.DATA_LENGTH/2 || ')',
'CHAR', t.DATA_TYPE || '(' || t.DATA_LENGTH || ')',
'NUMBER',t.DATA_TYPE || (nvl2(t.DATA_PRECISION,nvl2(decode(t.DATA_SCALE,0,null,t.DATA_SCALE),
'(' || t.DATA_PRECISION || ',' || t.DATA_SCALE || ')',
'(' || t.DATA_PRECISION || ')'),'(18)')),t.DATA_TYPE) AS jdbcType
FROM user_tab_columns t, user_col_comments c
WHERE t.TABLE_NAME = c.table_name
AND t.COLUMN_NAME = c.column_name
<if test="name != null and name != ''">
AND t.TABLE_NAME = upper(#{name})
</if>
ORDER BY t.COLUMN_ID
</if>

<if test="dbName == 'mysql'">
SELECT t.COLUMN_NAME AS name, (CASE WHEN t.IS_NULLABLE = 'YES' THEN '1' ELSE '0' END) AS isNull,
(t.ORDINAL_POSITION * 10) AS sort,t.COLUMN_COMMENT AS comments,t.COLUMN_TYPE AS jdbcType
FROM information_schema.`COLUMNS` t
WHERE t.TABLE_SCHEMA = (select database())
<if test="name != null and name != ''">
AND t.TABLE_NAME = upper(#{name})
</if>
ORDER BY t.ORDINAL_POSITION
</if>

<if test="dbName == 'oracle'">
SELECT lower(cu.COLUMN_NAME) AS columnName
FROM user_cons_columns cu, user_constraints au
WHERE cu.constraint_name = au.constraint_name
AND au.constraint_type = 'P'
AND au.table_name = upper(#{name})
</if>

<if test="dbName == 'mysql'">
SELECT lower(au.COLUMN_NAME) AS columnName
FROM information_schema.`COLUMNS` au
WHERE au.TABLE_SCHEMA = (select database())
AND au.COLUMN_KEY='PRI' AND au.TABLE_NAME = upper(#{name})
</if>