oracle中number对应java数据类型

原文链接：https://www.cnblogs.com/yadongliang/p/7727930.html

数据库中为number类型的字段，在Java类型中对应的有Integer和BigDecimal都会出现；
经测试发现当数据库为sql server和DB2时，用getObject()取出来时Integer类型，但是Oracle 中取出来就会是Integer或者BigDecimal类型。原因是oracle与java类型对应于number长度有关。

遇到该类型问题，若要判断每个数据库和数据库字段长度不同对应的java数据类型不同太过烦琐，可采用getString()来取值，统一先转为string来判断

查询所有用户

SELECT    t.username AS "dbName" FROM all_users t

oracle根据所属用户查询表名注释

SELECT
t.owner as "dbName",
t.table_name as "code",
t.comments as "tableName "
FROM
    all_tab_comments t 
WHERE
    t.table_type = 'TABLE' 
  AND t.owner = 'JEESITE'

oracle根据所属用户查询视图名和注释

SELECT
t.table_type tableType,
t.owner as "dbName",
t.table_name as "code",
t.comments as "tableName "
FROM
    all_tab_comments t 
WHERE
    t.table_type = 'VIEW' 
  AND t.owner = 'JEESITE'

通过所属用户 和表名查询字段信息

--表字段信息 SELECT
t.table_schema AS "dbName",
a.table_name AS "tableCode",
a.column_name AS "fieldCode",
a.data_type AS "dataType",
f.comments AS "fieldName" 
FROM
    all_tab_columns a
    INNER JOIN all_col_comments f ON a.OWNER = f.OWNER 
    AND a.table_name = f.table_name 
    AND a.column_name = f.column_name 
WHERE
    a.OWNER =? 
    AND a.TABLE_NAME =?