SELECT 
    COLUNAS.COLUMN_NAME AS COLUNA,
    COLUNAS.DATA_TYPE AS TIPO,
    DECODE(COLUNAS.DATA_PRECISION, NULL, COLUNAS.CHAR_COL_DECL_LENGTH, COLUNAS.DATA_PRECISION)  AS TAMANHO,
    COLUNAS.NULLABLE AS EH_NULO
 
FROM 
    USER_TABLES TABELAS,
    USER_TAB_COLUMNS COLUNAS
WHERE 
    -- JOINS 
    TABELA.TABLE_NAME = COLUNAS.TABLE_NAME
    AND TABELA.TABLE_NAME = 'TBL_TESTE'