[英]Type mismatch: cannot convert from element type Object to String JDBC MetaData
[英]JDBC : get the type of an array from the metadata
是否可以從JDBC元數據結構中獲取數組列的類型?
re = openedConnection.getMetaData().getColumns(...)
while (rs.next())
{
final String columnName = rs.getString("COLUMN_NAME");
final int columnType = rs.getInt("DATA_TYPE");
...
類型返回ARRAY,但返回什么數組(整數,文本,數字...)?
理想情況下,數據庫獨立(Oracle和Postgres支持對MySQL或SQL Server不確定)
使用java.sql.ResultSetMetaData.getColumnTypeName()
:
Oracle安裝程序 :
CREATE OR REPLACE TYPE random_array IS TABLE OF VARCHAR2(42);
/
Java的 :
Class.forName("oracle.jdbc.OracleDriver");
Connection con = DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:orcl",
"username",
"password"
);
PreparedStatement st = con.prepareStatement(
"SELECT random_array( 'a', 'b', 'c' ) AS array FROM DUAL"
);
ResultSet rs = st.executeQuery();
while( rs.next() )
{
String type = rs.getMetaData().getColumnTypeName(1);
String[] data = (String[]) rs.getArray(1).getArray();
System.out.println( type + ": " + Arrays.toString( data ) );
}
st.close();
con.close();
輸出 :
SCHEMA_NAME.RANDOM_ARRAY: [a, b, c]
然后,如果您想返回到Oracle並查找集合元素的類型,可以使用:
SELECT ELEM_TYPE_NAME,
LENGTH,
PRECISION,
SCALE
FROM ALL_COLL_TYPES
WHERE TYPE_NAME = 'RANDOM_ARRAY'
AND OWNER = 'SCHEMA_NAME';
哪個輸出:
ELEM_TYPE_NAME LENGTH PRECISION SCALE
-------------- ------ --------- -----
VARCHAR2 42
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