Apr 1, 2010

What is SQL Loader with Examples

What is SQL Loader

SQL LOADER is an Oracle utility used to load data into table given a datafile which has the records that need to be loaded. SQL*Loader takes data file, as well as a control file, to insert data into the table. When a Control file is executed, it can create Three (3) files called a
 log file, bad file or reject file, discard file.

  • Log file tells you the state of the tables and indexes and the number of logical records already read from the input datafile. This information can be used to resume the load where it left off.
  • Bad file or reject file gives you the records that were rejected because of formatting errors or because they caused Oracle errors.
  • Discard file specifies the records that do not meet any of the loading criteria like when any of the WHEN clauses specified in the control file. These records differ from rejected records.

What is Structure of the data file:
The data file can be in fixed record format or variable record format.

Fixed Record Format would look like the below. In this case you give a specific position where the Control file can expect a data field:

7369 SMITH      CLERK        7902  12/17/1980         800                  
7499 ALLEN      SALESMAN  7698  2/20/1981           1600    
7521 WARD      SALESMAN  7698  2/22/1981           1250    
7566 JONES      MANAGER   7839  4/2/1981             2975             
7654 MARTIN    SALESMAN  7698  9/28/1981           1250    
7698 BLAKE      MANAGER   7839  5/1/1981             2850             
7782 CLARK      MANAGER   7839  6/9/1981             2450             
7788 SCOTT      ANALYST    7566  12/9/1982           3000             
7839 KING        PRESIDENT          11/17/1981         5000             
7844 TURNER    SALESMAN  7698  9/8/1981            1500           
7876 ADAMS     CLERK         7788  1/12/1983          1100             
7900 JAMES      CLERK         7698  12/3/1981          950              
7902 FORD        ANALYST     7566  12/3/1981          3000            
7934 MILLER     CLERK         7782  1/23/1982          1300            

Variable Record Format would like below where the data fields are separated by a delimiter.
Note: The Delimiter can be anything you like. In this case it is "|"


Structure of a Control file:

Sample CTL file for loading a Variable record data file:

OPTIONS (SKIP = 1)   --The first row in the data file is skipped without loading
INFILE '$FILE'             -- Specify the data file path and name
APPEND                       -- type of loading (INSERT, APPEND, REPLACE, TRUNCATE
INTO TABLE "APPS"."BUDGET"   -- the table to be loaded into
FIELDS TERMINATED BY '|'           -- Specify the delimiter if variable format datafile
 OPTIONALLY ENCLOSED BY '"'   --the values of the data fields may be enclosed in "
TRAILING NULLCOLS     -- columns that are not present in the record treated as null
  (ITEM_NUMBER    "TRIM(:ITEM_NUMBER)", -- Can use all SQL functions on columns
  QTY                 DECIMAL EXTERNAL,
  MONTH           "to_char(LAST_DAY(ADD_MONTHS(SYSDATE,-1)),'DD-MON-YY')" ,
DIVISION_CODE    CONSTANT "AUD"  -- Can specify constant value instead of
                                                                          Getting value from datafile

OPTION statement precedes the LOAD DATA statement. The OPTIONS parameter allows you to specify runtime arguments in the control file, rather than on the command line. The following arguments can be specified using the OPTIONS parameter.
SKIP = n -- Number of logical records to skip (Default 0)
LOAD = n -- Number of logical records to load (Default all)
ERRORS = n -- Number of errors to allow (Default 50)
ROWS = n   -- Number of rows in conventional path bind array or between direct path data saves (Default: Conventional Path 64, Direct path all)
BINDSIZE = n -- Size of conventional path bind array in bytes (System-dependent default)
SILENT = {FEEDBACK | ERRORS | DISCARDS | ALL} -- Suppress messages during run
                (header, feedback, errors, discards, partitions, all)
DIRECT = {TRUE | FALSE} --Use direct path (Default FALSE)
PARALLEL = {TRUE | FALSE} -- Perform parallel load (Default FALSE)

LOAD DATA statement is required at the beginning of the control file.

INFILE: INFILE keyword is used to specify location of the datafile or datafiles.
INFILE * specifies that the data is found in the control file and not in an external file. INFILE '$FILE', can be used to send the filepath and filename as a parameter when registered as a concurrent program.
INFILE   '/home/vision/kap/import2.csv' specifies the filepath and the filename.

Example where datafile is an external file:
INFILE   '/home/vision/kap/import2.csv'
INTO TABLE kap_emp
( emp_num, emp_name, department_num, department_name )

Example where datafile is in the Control file:
INTO TABLE kap_emp
FIELDS TERMINATED BY ","              
( emp_num, emp_name, department_num, department_name )

Example where file name and path is sent as a parameter when registered as a concurrent program
INTO TABLE kap_emp
FIELDS TERMINATED BY ","              
( emp_num, emp_name, department_num, department_name )

INSERT   -- If the table you are loading is empty, INSERT can be used.
APPEND  -- If data already exists in the table, SQL*Loader appends the new rows to it. If data doesn't already exist, the new rows are simply loaded.
REPLACE -- All rows in the table are deleted and the new data is loaded
TRUNCATE -- SQL*Loader uses the SQL TRUNCATE command.

INTO TABLE is required to identify the table to be loaded into. In the above example INTO TABLE "APPS"."BUDGET", APPS refers to the Schema and BUDGET is the Table name.
FIELDS TERMINATED BY specifies how the data fields are terminated in the datafile.(If the file is Comma delimited or Pipe delimited etc)

OPTIONALLY ENCLOSED BY '"' specifies that data fields may also be enclosed by quotation marks.
TRAILING NULLCOLS clause tells SQL*Loader to treat any relatively positioned columns that are not present in the record as null columns.

How to Loading a fixed format data file:
INFILE 'sample.dat'
(      empno         POSITION(01:04)   INTEGER EXTERNAL,
       ename          POSITION(06:15)   CHAR,
       job            POSITION(17:25)   CHAR,
       mgr            POSITION(27:30)   INTEGER EXTERNAL,
       sal            POSITION(32:39)   DECIMAL EXTERNAL,
       comm           POSITION(41:48)   DECIMAL EXTERNAL,
       deptno         POSITION(50:51)   INTEGER EXTERNAL)

What are Steps to Run the SQL* LOADER from UNIX:
At the prompt, invoke SQL*Loader as follows:
      sqlldr USERID=scott/tiger CONTROL= LOG=

SQL*Loader loads the tables, creates the log file, and returns you to the system prompt. You can check the log file to see the results of running the case study.

How to Register as concurrent Program:

Place the Control file in $CUSTOM_TOP/bin.
Define the Executable. Give the Execution Method as SQL*LOADER.
Define the Program. Add the Parameter for FILENAME.

 How to Skip columns:
You can skip columns using the 'FILLER' option.

Load Data
name Filler,
Empno ,

here the column name will be skipped.

No comments:

OraApps Search

Custom Search

Search This Blog