crystal reports 2008 barcode 128 DATA LOADING AND UNLOADING in Objective-C

Creation Data Matrix in Objective-C DATA LOADING AND UNLOADING

Often, you have a flat file generated from some external system, and this file is a fixed-length file with positional data. For example, the NAME field is in bytes 1 to 10, the ADDRESS field is in bytes 11 to 35, and so on. We will look at how SQLLDR can import this kind of data for us. This fixed-width, positional data is the optimal data format for SQLLDR to load. It will be the fastest way to process, as the input data stream is somewhat trivial to parse. SQLLDR will have stored fixed-byte offsets and lengths into data records, and extracting a given field is very simple. If you have an extremely large volume of data to load, converting it to a fixed position format is generally the best approach. The downside to a fixed-width file is, of course, that it can be much larger than a simple, delimited file format. To load fixed-width positional data, you will use the POSITION keyword in the control file, for example: LOAD DATA INFILE * INTO TABLE DEPT REPLACE ( DEPTNO position(1:2), DNAME position(3:16), LOC position(17:29) ) BEGINDATA 10Accounting Virginia,USA This control file does not employ the FIELDS TERMINATED BY clause; rather, it uses POSITION to tell SQLLDR where fields begin and end. Note that with the POSITION clause we could use overlapping positions, and go back and forth in the record. For example, if we were to alter the DEPT table as follows ops$tkyte@ORA11GR2> alter table dept add entire_line varchar2(29); Table altered. and then use the following control file LOAD DATA INFILE * INTO TABLE DEPT REPLACE ( DEPTNO position(1:2), DNAME position(3:16), LOC position(17:29), ENTIRE_LINE position(1:29) ) BEGINDATA 10Accounting Virginia,USA the field ENTIRE_LINE is defined as POSITION(1:29). It extracts its data from all 29 bytes of input data, whereas the other fields are substrings of the input data. The outcome of this control file will be as follows:

ops$tkyte@ORA11GR2> select * from dept; DEPTNO DNAME LOC ENTIRE_LINE ---------- -------------- ------------- ----------------------------10 Accounting Virginia,USA 10Accounting Virginia,USA When using POSITION, we can use relative or absolute offsets. In the preceding example, we used absolute offsets. We specifically denoted where fields begin and where they end. We could have written the preceding control file as follows: LOAD DATA INFILE * INTO TABLE DEPT REPLACE ( DEPTNO position(1:2), DNAME position(*:16), LOC position(*:29), ENTIRE_LINE position(1:29) ) BEGINDATA 10Accounting Virginia,USA The * instructs the control file to pick up where the last field left off. Therefore (*:16) is just the same as (3:16) in this case. Notice that you can mix relative and absolute positions in the control file. Additionally, when using the * notation, you can add to the offset. For example, if DNAME started 2 bytes after the end of DEPTNO, we could have used (*+2:16). In this example, the effect would be identical to using (5:16). The ending position in the POSITION clause must be the absolute column position where the data ends. At times, it can be easier to specify just the length of each field, especially if they are contiguous, as in the preceding example. In this fashion, we would just have to tell SQLLDR the record starts at byte 1, and then specify the length of each field. This will save us from having to compute start and stop byte offsets into the record, which can be hard at times. In order to do this, we ll leave off the ending position and instead specify the length of each field in the fixed-length record as follows: LOAD DATA INFILE * INTO TABLE DEPT REPLACE ( DEPTNO position(1) char(2), DNAME position(*) char(14), LOC position(*) char(13), ENTIRE_LINE position(1) char(29) ) BEGINDATA 10Accounting Virginia,USA Here we had to tell SQLLDR only where the first field begins and its length. Each subsequent field starts where the last one left off and continues for a specified length. It is not until the last field that we have to specify a position again, since this field goes back to the beginning of the record.