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Oracle® Database JDBC Developer's Guide and Reference
10g Release 2 (10.2)

Part Number B14355-02
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A Reference Information

This appendix contains detailed Java Database Connectivity (JDBC) reference information, including the following topics:

Valid SQL-JDBC Data Type Mappings

Table 13-1 describes the default mappings between Java classes and SQL data types supported by the Oracle JDBC drivers. Compare the contents of the JDBC Type Codes, Standard Java Types, and SQL Data Types columns in Table 13-1 with the contents of Table A-1.

Table A-1 lists all the possible Java types to which a given SQL data type can be validly mapped. The Oracle JDBC drivers will support these nondefault mappings. For example, to materialize SQL CHAR data in an oracle.sql.CHAR object, use the getCHAR method. To materialize it as a java.math.BigDecimal object, use the getBigDecimal method.

Notes:

For classes where oracle.sql.ORAData appears in italic, these can be generated by JPublisher.

Table A-1 Valid SQL Data Type-Java Class Mappings

These SQL data types: Can be materialized as these Java types:

CHAR, VARCHAR2, LONG

oracle.sql.CHAR


java.lang.String


java.sql.Date


java.sql.Time


java.sql.Timestamp


java.lang.Byte


java.lang.Short


java.lang.Integer


java.lang.Long


java.lang.Float


java.lang.Double


java.math.BigDecimal


byte, short, int, long, float, double

DATE

oracle.sql.DATE


java.sql.Date


java.sql.Time


java.sql.Timestamp


java.lang.String

NUMBER

oracle.sql.NUMBER


java.lang.Byte


java.lang.Short


java.lang.Integer


java.lang.Long


java.lang.Float


java.lang.Double


java.math.BigDecimal


byte, short, int, long, float, double

OPAQUE

oracle.sql.OPAQUE

RAW, LONG RAW

oracle.sql.RAW

 

byte[]

ROWID

oracle.sql.CHAR


oracle.sql.ROWID


java.lang.String

BFILE

oracle.sql.BFILE

BLOB

oracle.sql.BLOB


java.sql.Blob

CLOB

oracle.sql.CLOB


java.sql.Clob

TIMESTAMP

java.sql.Date, oracle.sql.DATE, java.sql.Time, java.sql.Timestamp, oracle.sql.TIMESTAMP, java.lang.String, byte[]

TIMESTAMP WITH TIME ZONE

java.sql.Date, oracle.sql.DATE, java.sql.Time, java.sql.Timestamp, oracle.sql.TIMESTAMPTZ, java.lang.String, byte[]

TIMESTAMP WITH LOCAL TIME ZONE

java.sql.Date, oracle.sql.DATE, java.sql.Time, java.sql.Timestamp, oracle.sql.TIMESTAMPLTZ, java.lang.String, byte[]

Object types

oracle.sql.STRUCT


java.sql.Struct


java.sql.SqlData


oracle.sql.ORAData

Reference types

oracle.sql.REF


java.sql.Ref


oracle.sql.ORAData

Nested table types and VARRAY types

oracle.sql.ARRAY


java.sql.Array


oracle.sql.ORAData


Notes:

  • The type UROWID is not supported.

  • The oracle.sql.Datum class is abstract. The value passed to a parameter of type oracle.sql.Datum must be of the Java type corresponding to the underlying SQL type. Likewise, the value returned by a method with return type oracle.sql.Datum must be of the Java type corresponding to the underlying SQL type.

Supported SQL and PL/SQL Data Types

The tables in this section list SQL and PL/SQL data types, and whether the Oracle JDBC drivers support them. Table A-2 describes Oracle JDBC driver support for SQL data types.

Table A-2 Support for SQL Data Types

SQL Data Type Supported by JDBC Drivers?

BFILE

yes

BLOB

yes

CHAR

yes

CLOB

yes

DATE

yes

NCHAR

no (see Note)

NCHAR VARYING

no

NUMBER

yes

NVARCHAR2

no (see Note)

RAW

yes

REF

yes

ROWID

yes

UROWID

no

VARCHAR2

yes


Note:

The types NCHAR and NVARCHAR2 are supported indirectly. There is no corresponding java.sql.Types type, but if your application calls formOfUse(NCHAR), then these types can be accessed.

Table A-3 describes Oracle JDBC support for the ANSI-supported SQL data types.

Table A-3 Support for ANSI-92 SQL Data Types

ANSI-Supported SQL Data Type Supported by JDBC Drivers?

CHARACTER

yes

DEC

yes

DECIMAL

yes

DOUBLE PRECISION

yes

FLOAT

yes

INT

yes

INTEGER

yes

NATIONAL CHARACTER

no

NATIONAL CHARACTER VARYING

no

NATIONAL CHAR

yes

NATIONAL CHAR VARYING

no

NCHAR

yes

NCHAR VARYING

no

NUMERIC

yes

REAL

yes

SMALLINT

yes

VARCHAR

yes


Table A-4 describes Oracle JDBC driver support for SQL User-Defined types.

Table A-4 Support for SQL User-Defined Types

SQL User-Defined type Supported by JDBC Drivers?

OPAQUE

yes

Reference types

yes

Object types (JAVA_OBJECT)

yes

Nested table types and VARRAY types

yes


Table A-5 describes Oracle JDBC driver support for PL/SQL data types. Note that PL/SQL data types include these categories:

Table A-5 Support for PL/SQL Data Types

PL/SQL Data Type Supported by JDBC Drivers?

Scalar Types:


BINARY INTEGER

yes

DEC

yes

DECIMAL

yes

DOUBLE PRECISION

yes

FLOAT

yes

INT

yes

INTEGER

yes

NATURAL

yes

NATURALn

no

NUMBER

yes

NUMERIC

yes

PLS_INTEGER

yes

POSITIVE

yes

POSITIVEn

no

REAL

yes

SIGNTYPE

yes

SMALLINT

yes

Scalar Character Types:


CHAR

yes

CHARACTER

yes

LONG

yes

LONG RAW

yes

NCHAR

no (see Note)

NVARCHAR2

no (see Note)

RAW

yes

ROWID

yes

STRING

yes

UROWID

no

VARCHAR

yes

VARCHAR2

yes

BOOLEAN

yes

DATE

yes

Composite Types:


RECORD

no

TABLE

no

VARRAY

yes

Reference Types:


REF CURSOR types

yes

object reference types

yes

LOB Types:


BFILE

yes

BLOB

yes

CLOB

yes

NCLOB

yes


Notes:

  • The types NATURAL, NATURALn, POSITIVE, POSITIVEn, and SIGNTYPE are subtypes of BINARY INTEGER.

  • The types DEC, DECIMAL, DOUBLE PRECISION, FLOAT, INT, INTEGER, NUMERIC, REAL, and SMALLINT are subtypes of NUMBER.

  • The types NCHAR and NVARCHAR2 are supported indirectly. There is no corresponding java.sql.Types type, but if your application calls formOfUse(NCHAR), then these types can be accessed. Refer to "NCHAR, NVARCHAR2, NCLOB and the defaultNChar Property" for details.

Embedded SQL92 Syntax

The Oracle JDBC drivers support some embedded SQL92 syntax, which is the syntax that you specify between curly braces. The current support is basic. This section describes the support offered by the drivers for the following SQL92 constructs:

Where driver support is limited, these sections also describe possible workarounds.

Disabling Escape Processing

Escape processing for SQL92 syntax is enabled by default, which results in the JDBC driver performing escape substitution before sending the SQL code to the database. If you want the driver to use regular Oracle SQL syntax, which is more efficient than SQL92 syntax and escape processing, then use this statement:

stmt.setEscapeProcessing(false);

Time and Date Literals

Databases differ in the syntax they use for date, time, and timestamp literals. JDBC supports dates and times written only in a specific format. This section describes the formats you must use for date, time, and timestamp literals in SQL statements.

Date Literals

The JDBC drivers support date literals in SQL statements written in the format:

{d 'yyyy-mm-dd'}

Where yyyy-mm-dd represents the year, month, and day. For example:

{d '1995-10-22'}

The JDBC drivers will replace this escape clause with the equivalent Oracle representation: "22 OCT 1995".

The following code snippet contains an example of using a date literal in a SQL statement.

// Connect to the database
// You can put a database name after the @ sign in the connection URL.
OracleDataSource ods = new OracleDataSource();
ods.setURL("jdbc:oracle:oci:@");
ods.setUser("scott");
ods.setPassword("tiger");
Connection conn = ods.getConnection();

// Create a Statement
Statement stmt = conn.createStatement ();

// Select the ename column from the emp table where the hiredate is Jan-23-1982
ResultSet rset = stmt.executeQuery 
                 ("SELECT ename FROM emp WHERE hiredate = {d '1982-01-23'}");

// Iterate through the result and print the employee names
while (rset.next ())
   System.out.println (rset.getString (1));

Time Literals

The JDBC drivers support time literals in SQL statements written in the format:

{t 'hh:mm:ss'}

where, hh:mm:ss represents the hours, minutes, and seconds. For example:

{t '05:10:45'}

The JDBC drivers will replace this escape clause with the equivalent Oracle representation: "05:10:45".

If the time is specified as:

{t '14:20:50'}

Then the equivalent Oracle representation would be "14:20:50", assuming the server is using a 24-hour clock.

This code snippet contains an example of using a time literal in a SQL statement.

ResultSet rset = stmt.executeQuery 
                 ("SELECT ename FROM emp WHERE hiredate = {t '12:00:00'}");

Timestamp Literals

The JDBC drivers support timestamp literals in SQL statements written in the format:

{ts 'yyyy-mm-dd hh:mm:ss.f...'} 

where yyyy-mm-dd hh:mm:ss.f... represents the year, month, day, hours, minutes, and seconds. The fractional seconds portion (.f...) is optional and can be omitted. For example: {ts '1997-11-01 13:22:45'} represents, in Oracle format, NOV 01 1997 13:22:45.

This code snippet contains an example of using a timestamp literal in a SQL statement.

ResultSet rset = stmt.executeQuery 
    ("SELECT ename FROM emp WHERE hiredate = {ts '1982-01-23 12:00:00'}");

Scalar Functions

The Oracle JDBC drivers do not support all scalar functions. To find out which functions the drivers support, use the following methods supported by the Oracle-specific oracle.jdbc.OracleDatabaseMetaData class and the standard Java java.sql.DatabaseMetadata interface:

  • getNumericFunctions()

    Returns a comma-delimited list of math functions supported by the driver. For example, ABS, COS, SQRT.

  • getStringFunctions()

    Returns a comma-delimited list of string functions supported by the driver. For example, ASCII, LOCATE.

  • getSystemFunctions()

    Returns a comma-delimited list of system functions supported by the driver. For example, DATABASE, USER.

  • getTimeDateFunctions()

    Returns a comma-delimited list of time and date functions supported by the driver. For example, CURDATE, DAYOFYEAR, HOUR.

    Note:

    Oracle JDBC drivers support fn, the function keyword.

LIKE Escape Characters

The characters % and _ have special meaning in SQL LIKE clauses. You use % to match zero or more characters and _ to match exactly one character. If you want to interpret these characters literally in strings, then you precede them with a special escape character. For example, if you want to use ampersand (&) as the escape character, then you identify it in the SQL statement as:

Statement stmt = conn.createStatement ();

// Select the empno column from the emp table where the ename starts with '_'
ResultSet rset = stmt.executeQuery
          ("SELECT empno FROM emp WHERE ename LIKE '&_%' {ESCAPE '&'}");

// Iterate through the result and print the employee numbers
while (rset.next ())
   System.out.println (rset.getString (1));

Note:

If you want to use the backslash character (\) as an escape character, then you must enter it twice, that is, \\. For example:
ResultSet rset = stmt.executeQuery("SELECT empno FROM emp
                WHERE ename LIKE '\\_%' {escape '\\'}");

Outer Joins

Oracle JDBC drivers do not support the outer join syntax. The workaround is to use Oracle outer join syntax:

Instead of:

Statement stmt = conn.createStatement ();
ResultSet rset = stmt.executeQuery
     ("SELECT ename, dname 
       FROM {OJ dept LEFT OUTER JOIN emp ON dept.deptno = emp.deptno} 
       ORDER BY ename");

Use Oracle SQL syntax:

Statement stmt = conn.createStatement ();
ResultSet rset = stmt.executeQuery
     ("SELECT ename, dname 
       FROM emp a, dept b WHERE a.deptno = b.deptno(+)
       ORDER BY ename");

Function Call Syntax

Oracle JDBC drivers support the following procedure and function call syntax:

Procedure calls:

{ call procedure_name (argument1, argument2,...) } 

Function calls:

{ ? = call procedure_name (argument1, argument2,...) }

SQL92 to SQL Syntax Example

You can write a simple program to translate SQL92 syntax to standard SQL syntax. The following program prints the comparable SQL syntax for SQL92 statements for function calls, date literals, time literals, and timestamp literals. In the program, the oracle.jdbc.OracleSql class parse() method performs the conversions.

import oracle.jdbc.OracleSql; 
 
public class Foo 
{ 
   public static void main (String args[]) throws Exception 
   { 
      show ("{call foo(?, ?)}"); 
      show ("{? = call bar (?, ?)}"); 
      show ("{d '1998-10-22'}"); 
      show ("{t '16:22:34'}"); 
      show ("{ts '1998-10-22 16:22:34'}"); 
   } 
 
   public static void show (String s) throws Exception 
   { 
      System.out.println (s + " => " + 
         oracle.jdbc.OracleDriver.processSqlEscapes(s)); 
   } 
}

The following code is the output that prints the comparable SQL syntax.

{call foo(?, ?)} => BEGIN foo(:1, :2); END; 
{? = call bar (?, ?)} => BEGIN :1 := bar (:2, :3); END; 
{d '1998-10-22'} => TO_DATE ('1998-10-22', 'YYYY-MM-DD') 
{t '16:22:34'} => TO_DATE ('16:22:34', 'HH24:MI:SS') 
{ts '1998-10-22 16:22:34'} => TO_DATE ('1998-10-22 16:22:34', 'YYYY-MM-DD 
HH24:MI:SS') 

Oracle JDBC Notes and Limitations

The following limitations exist in the Oracle JDBC implementation, but all of them are either insignificant or have easy workarounds. This section covers the following topics:

CursorName

Oracle JDBC drivers do not support the get getCursorName and setCursorName methods, because there is no convenient way to map them to Oracle constructs. Oracle recommends using ROWID instead.

See Also:

"Oracle ROWID Type" for more information on how to use and manipulate ROWIDs.

SQL92 Outer Join Escapes

Oracle JDBC drivers do not support SQL92 outer join escapes. Use Oracle SQL syntax with + instead.

PL/SQL TABLE, BOOLEAN, and RECORD Types

It is not feasible for Oracle JDBC drivers to support calling arguments or return values of the PL/SQL RECORD, BOOLEAN, or table with non-scalar element types. However, Oracle JDBC drivers support PL/SQL index-by table of scalar element types.

As a workaround to PL/SQL RECORD, BOOLEAN, or non-scalar table types, create wrapper procedures that handle the data as types supported by JDBC. For example, to wrap a stored procedure that uses PL/SQL boolean, create a stored procedure that takes a character or number from JDBC and passes it to the original procedure as BOOLEAN or, for an output parameter, accepts a BOOLEAN argument from the original procedure and passes it as a CHAR or NUMBER to JDBC. Similarly, to wrap a stored procedure that uses PL/SQL records, create a stored procedure that handles a record in its individual components, such as CHAR and NUMBER, or in a structured object type. To wrap a stored procedure that uses PL/SQL tables, break the data into components or perhaps use Oracle collection types.

See Also:

"Boolean Parameters in PL/SQL Stored Procedures" for an example of a workaround for BOOLEAN.

IEEE 754 Floating Point Compliance

The arithmetic for the Oracle NUMBER type does not comply with the IEEE 754 standard for floating-point arithmetic. Therefore, there can be small disagreements between the results of computations performed by Oracle and the same computations performed by Java.

Oracle stores numbers in a format compatible with decimal arithmetic and guarantees 38 decimal digits of precision. It represents zero, minus infinity, and plus infinity exactly. For each positive number it represents, it represents a negative number of the same absolute value.

It represents every positive number between 10-30 and (1 – 10-38) * 10126 to full 38-digit precision.

Catalog Arguments to DatabaseMetaData Calls

Certain DatabaseMetaData methods define a catalog parameter. This parameter is one of the selection criteria for the method. Oracle does not have multiple catalogs, but it does have packages.

See Also:

"DatabaseMetaData TABLE_REMARKS Reporting" for information on how the Oracle JDBC drivers treat the catalog argument.

SQLWarning Class

The java.sql.SQLWarning class provides information on a database access warning. Warnings typically contain a description of the warning and a code that identifies the warning. Warnings are silently chained to the object whose method caused it to be reported. The Oracle JDBC drivers generally do not support SQLWarning. As an exception to this, scrollable result set operations do generate SQL warnings, but the SQLWarning instance is created on the client, not in the database.

Binding Named Parameters

Binding by name is not supported when using the setXXX methods. Under certain circumstances, previous versions of the Oracle JDBC drivers have allowed binding statement variables by name when using the setXXX methods. In the following statement, the named variable EmpId would be bound to the integer 314159.

PreparedStatement p = conn.prepareStatement
  ("SELECT name FROM emp WHERE id = :EmpId");
  p.setInt(1, 314159);

This capability to bind by name using the setXXX methods is not part of the JDBC specification, and Oracle does not support it. The JDBC drivers can throw a SQLException or produce unexpected results. In Oracle Database 10g JDBC drivers, bind by name is supported using the setXXXAtName methods.

Retaining Bound Values

Before Oracle9i Database, the Oracle JDBC drivers did not retain bound values from one call of execute to the next as specified in JDBC 1.0. All releases after Oracle9i Database have retained bound values. For example:

PreparedStatement p = conn.prepareStatement
    ("SELECT name FROM emp WHERE id = ? AND dept = ?");
p.setInt(1, 314159); 
p.setString(2, "SALES"); 
ResultSet r1 = p.execute(); 
p.setInt(1, 425260); 
ResultSet r2 = p.execute();  

Previously, a SQLException would be thrown by the second execute call because no value was bound to the second argument. In Oracle Database 10g, the second execute will return the correct value, retaining the binding of the second argument to the string SALES.

If the retained bound value is a stream, then the Oracle JDBC drivers will not reset the stream. Unless the application code resets, repositions, or otherwise modifies the stream, the subsequent calls to execute will send NULL as the value of the argument.