jdbc连接数据库获取所有表，表的字段及类型之Oracle

https://blog.csdn.net/hhhliushen/article/details/105272439
昨天写的这篇jdbc连接数据库获得所有表 表的所有字段及类型对于mysql来说速度还是可以的，但是对于oracle来说 真的是太慢了。我只好用sql来获取。下面贴上我的代码。

• 获取当前登录用户的所有表

select table_name from all_tables a where a.OWNER = upper('username')

public static Map<String,Integer> getTables(Connection conn,String username) {
    Map<String, Integer> map = new HashMap<>();
    PreparedStatement stmt;
    String createSql = "select table_name from all_tables a where a.OWNER = upper('"+username+"')";
    try {
        stmt = conn.prepareStatement(createSql);
        ResultSet rs = stmt.executeQuery(createSql);
        while (rs.next()) {
            String name = rs.getString("table_name");
            int count = getTablesCount(conn,name);
            map.put(name,count);
        }
    } catch (SQLException e) {
        return map;
    }finally {
        return map;
    }
}

• 获取表的行数

SELECT count(1) as cou from tablename

public static Integer getTablesCount(Connection conn,String name) {
    PreparedStatement stmt;
    String createSql = "SELECT count(1) as cou from "+name;
    int count = 0;
    try {
        stmt = conn.prepareStatement(createSql);
        ResultSet rs = stmt.executeQuery(createSql);
        while (rs.next()) {
            count = rs.getInt("cou");
        }
    } catch (SQLException e) {
        return count;
    }finally {
        return count;
    }
}

• 获取指定表的所有列

select column_name,data_type from all_tab_columns c where c.TABLE_NAME like 'tablename'

public static Map<String,String> getColumn(Connection conn,String tableName) {
    Map<String,String> map = new HashMap<>();
    PreparedStatement stmt;
    String createSql = "select column_name,data_type from all_tab_columns c where c.TABLE_NAME like '"+tableName+"'";
    try {
        stmt = conn.prepareStatement(createSql);
        ResultSet rs = stmt.executeQuery(createSql);
        while (rs.next()) {
            String name = rs.getString("column_name");
            String type = rs.getString("data_type");
            map.put(name,type);
        }
    } catch (SQLException e) {
        return map;
    }finally {
        return map;
    }
}

• 获取指定表的主键

select column_name from user_cons_columns u,user_constraints c where u.table_name = 'tablename' and u.constraint_name = c.index_name and c.constraint_type ='P'

public static List<String> getPrimaryKey(Connection conn,String tableName){
    List<String> PrimaryKeysist = new ArrayList<String>();
    String createSql = "select column_name from user_cons_columns u,user_constraints c where u.table_name = '"+tableName+"' and u.constraint_name = c.index_name and c.constraint_type ='P'";
    PreparedStatement stmt;
    try {
        stmt = conn.prepareStatement(createSql);
        ResultSet rs = stmt.executeQuery(createSql);
        while (rs.next()) {
            String COLUMN_NAME = rs.getString("column_name");
            PrimaryKeysist.add(COLUMN_NAME);
        }
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return PrimaryKeysist;
}