尝试使用jdbc元数据获取列的列大小

Question

I am trying to recreate a schema for a table using only the metadata from jdbc.

I have it all working except for the column size eg. location VARCHAR(10)

Currently for every column it is printing VARCHAR(2000000000)

The code:

ResultSet rs = databaseMetaData.getColumns(null, null, tableName, null);
while(rs.next()) {
  int columnSize = rs.getInt("COLUMN_SIZE");
}

The expected output is the number used when creating the table that is in the schema but it always returns 2000000000. Is there something simple I am missing?

Answer 1

The tags of your question indicate that you are using SQLite.

The documentation , chapter 2.2 Affinity Name Examples, states:

Note that numeric arguments in parentheses that following the type name (ex: "VARCHAR(255)") are ignored by SQLite - SQLite does not impose any length restrictions (other than the large global SQLITE_MAX_LENGTH limit) on the length of strings, BLOBs or numeric values.

Since SQLite doesn't use the length information, for COLUMN_SIZE it simply returns the maximum size of character based columns.

Answer 2

Try using the method

databaseMetaData.getColumnDisplaySize(int column)

where the column parameter is the number of column in the table. Source: https://docs.oracle.com/javase/7/docs/api/java/sql/ResultSetMetaData.html