MySQL

DB2 UDB

Comment

LPAD

no equivalent. Implement 

Refer to UDF LPAD in 

using UDF

Appendix A.3,  Sample 

code for RPAD and LPAD 

functions  on page 339

MID

SUBSTR

Function MID is synonym 

for SUBSTR

REVERSE

SET 

(RESTSTR, LEN) = (INSTR, 

Implement UDF. For the 

LENGTH(INSTR));

complete code of the 

WHILE 

LEN > 0 

DO

SET 

(REVSTR, RESTSTR, LEN)

= 

example refer to IBM DB2 

(SUBSTR(RESTSTR, 1, 1) || 

UDB SQL Reference, 

REVSTR,SUBSTR(RESTSTR, 2, 

LEN   1),LEN   1);

Volume 1, V8, SC09 4844

END WHILE;

RPAD

no equivalent. Implement 

Refer to UDF RPAD in 

using UDF

Appendix A.3,  Sample 

code for RPAD and LPAD 

functions  on page 339

STRCMP

CASE

Implement using CASE 

expression and VALUES 

statement

SUBSTRING_INDEX

no equivalent. Implement 

Refer to UDF 

using UDF

SUBSTRING_INDEX in 

Appendix A.7,  Sample 

code for 

SUBSTRING_INDEX  on 

page 360

TRIM (1 arg)

LTRIM,RTRIM

Requires string 

manipulation

TRIM; Many char 

LTRIM,RTRIM

Requires string 

extension

manipulation

TRIM; Substring extension

LTRIM,RTRIM

Requires string 

manipulation

7.1.7  Implicit casting of data types

We have found significant differences in the way MySQL and DB2 UDB handle 

the casting of data types. Unless explicitly using the CAST function, DB2 does 

not convert strings representing numeric values. Example 7 9 shows how 

MySQL implicitly casts the character value

 5

 to an integer value to resolve the 

query. Implicit casting is not only performed in unambiguous cases as shown in 

 Chapter 7. Application porting 

163