Using IBM-Informix datatypes with IDS 10 and web application server Keshava Murthy, IBM Informix Development

Transcription

1 IBM GLOBAL SERVICES Using IBM-Informix datatypes with IDS 10 and web application server Keshava Murthy, IBM Informix Development Sept , 2005 Orlando, FL 1

2 Agenda JDBC Datatypes IDS 10 Datatypes Java <> JDBC <> IDS 10 mappings J2EE 1.4 JDBC API Test Suite SQL99 Types, Opaque Types, JDBC

3 Use Cases IDS in J2EE paradigm/websphere Integration Websphere Application Server Client Browser Servlet Controller Java UDRs Informix Dynamic Server JSP EJB View Model 3 3

4 try { PreparedStatement pstmt = conn.preparestatement("select * from x " + "where a =?;"); pstmt.setint(1, 11); ResultSet r = pstmt.executequery(); while(r.next()) { short i = r.getshort(1); System.out.println("Select: column a = " + i); } r.close(); pstmt.close(); Catch { } 4 4

5 JDBC Type BIGINT BINARY BIT REF CHAR DATE DECIMAL DOUBLE FLOAT INTEGER LONGVARBINARY LONGVARCHAR NUMERIC NUMERIC REAL 5 IDS Type INT8 BYTE BOOLEAN Not Supported CHAR(n) DATE DECIMAL FLOAT FLOAT INTEGER BYTE or BLOB TEXT or CLOB DECIMAL MONEY SMALLFLOAT 5

6 JDBC Type SMALLINT TIME TIMESTAMP TINYINT VARBINARY VARCHAR BOOLEAN SMALLINT IDS Type SMALLINT DATETIME HOUR TO FRACTION DATETIME YEAR TO FRACTION(5) SMALLINT BYTE VARCHAR(m,r) BOOLEAN SMALLINT 6 6

7 JDBC (Generic SQL) Types TINYINT, SMALLINT, INTEGER, BIGINT byte vs short, short, int, long Java data types vs SQL data type (not) SMALLINT, INTEGER (portable) 7 TINYINT 8 bits signed or unsigned, SQL type supported by subset of DBs SMALLINT: 16 bit signed, SQL type most DBs implement as 16 bits INTEGER: 32 bits signed, widely supported BIGINT: 64 bits signed, nonstandard, sparse support Recommended mapping to Java (builtin vs Object) SQL and Java data types are not identical, and SQL types may varying from vendor to vendor; The JDBC Types allow portable code. For portable code (database independent) SMALLINT, INTEGER as 16 bit/32 bit signed is recommended 7

8 JDBC Types (cont d) REAL, DOUBLE, FLOAT float, double, double DECIMAL, NUMERIC java.math.bigdecimal 8 Single precision floating point, precision unspecified, most db matissa > 7, Double precision floating point, precision unspecified, most db matissa > 15, JDBC FLOAT equivalent to JDBC DOUBLE, avoid JDBC FLOAT because SQL FLOAT does not match Java float Decimal and Numeric are very similar, fixed precision, SQL92 data types, and widely implemented. Specify number of digits and scale. Scale is the number of digits after the decimal point. DECIMAL(n,m) supports at least n digits of precision. NUMERIC(n, m) supports exactly n digits precision. 8

9 JDBC Types (cont d) CHAR, VARCHAR, LONGVARCHAR String, String, String, (char[],char[],char[]) BINARY,VARBINARY, LONGVARB byte[], byte[],byte[] isolation level vs large data 9 CHAR and VARCHAR are SQL92 and are fixed or variable length strings, implemented by all major database No consistent mapping between JDBC LONGVARCHAR and SQL TYPES, All majors support some type of variable length of data Up to at least 1 giga byte; but the SQL type names vary. getasciistream and getcharacterstream provided more flexability for LONGVARCHAR. The java programmer do not need to distinguish between these datatypes. Keshav, encoding, size of data in server char(254) holds what? Bytes/chararacters SQL BINARY / VARBINARY / LONGVARCHARBINARY are nonstandard and support varies 9

10 JDBC Type (cont d) DATE, TIME, TIMESTAMP d/m/y, h:m:s, d/m/y h:m:s nano s no exact match in Java (java.util.date) java.sql.date, java.sql.time, java.sql.timestamp advanced methods to specific Time Zone 10 DATE/TIME/TIMESTAMP are SQL02 type, implemented by subset or small number of db vendors Java.util.Date represents a point in time as the number of milliseconds (long) since a reference time (TZ/local independent) Java.sql.Date/Time/Timestamp are based on java.util.date (number of millisecs (64 bits). Timestamp also has a nanosecond field. Millisecs vs nanoseconds and interchangable since common subclass. Java uses locale (TZ, daylight saving time) when converting from/to human understandable format to / from the number of millisecs. 10

11 JDBC Types (odd ones) BIT, BOOLEAN(3.0), NULL,OTHER boolean, boolean,?, java Object? 1 and 0 vs true and false vs t and f setnull(ix, java.sql.types.null) multiple mapping (ambiguous) 11 SQL92 BIT can be used as parameterized type. SQL BIT Datatype is only required in FULL sql92 implementations. Supported by subset of db vendors. For portablility, it is recommended to use JDBC.SMALLINT vs JDBC BIT. BOOLEAN added in jdk1.4 Portable code involving java boolean to SQL Datatype is non trivial What is SQL NULL, is it a data type or is it a value of null for a data type, If mapping of JDBC type to SQL type depends on column, column/parameter metadata may be required. 11

12 JDBC (SQL99) Types BLOB, CLOB, ARRAY java.sql.blob, Clob, Array standard implementation is locator & data SQL99 ARRAY is a column in a row rs.getarray(ix).getarray( ) Object[] rs.getblob.getbytes byte[] rs.getclob.getasciistream() getstring 12 Standard implementation is for java.sql.blob to remain valid until the transaction in which it is created is either committed or rolled back. (ditto, array, clob). These are predefined types (Informix does not suport java.sql.types.ref 12

13 JDBC (SQL99) Types DISTINCT,STRUCT,REF,JAVA_OBJECT Java type for base SQL type java.sql.struct one or more SQL types or customed mapped to a class (Java language) 13 13

14 Distinct types CREATE DISTINCT TYPE mymoney AS NUMERIC(10, 2); CREATE TABLE distinct_tab (mymoney_col mymoney); String s = "insert into distinct_tab (mymoney_col) values (?)"; System.out.println(s); pstmt = conn.preparestatement(s);... BigDecimal bigdecobj = new BigDecimal(123.45); pstmt.setbigdecimal(1, bigdecobj); System.out.println("setBigDecimal...ok"); pstmt.executeupdate(); 14 14

15 Collection Types CREATE TABLE tab (a set(integer not null), b integer); INSERT INTO tab VALUES ("set{1,2,3}", 10); PreparedStatement pstmt = conn.preparestatement("select a from tab"); ResultSet rs = pstmt.executequery(); rs.next(); java.sql.array array = rs.getarray(1); Object obj = array.getarray((long) 1, 2); int [] intarray = (int []) obj; // cast it to an array of ints int i; for (i=0; i < intarray.length; i++) { System.out.println("integer element = " + intarray[i]); } pstmt.close(); 15 15

16 Opaque Types (UDTs) Built-in Types Boolean, Lvarchar Blob, Clob UDT Manager Creating UDTs using Java Using UDT Manager in JDBC 16 16

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19 Keshava Murthy IBM 19 19