1. Updating Records in a Table
Chapter 5
Updating Records in a Table
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Foxpro Chapter 5

2. Updating a table
Updating a table refers to editing (changing) records, adding new records (inserting) or deleting records.
Contents in a table can be changed interactively using the BROWSE or EDIT Windows.
Alternatively they can be changed using a FoxPro command.
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3. Updating vs. Querying Updating: Querying:
changing the data value within a table or the structure of the table itself.
Querying:
reading data values but not changing them.
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4. Ways to update Editing && fields of a record Inserting && a record
Deleting && a record
Importing && a file
Exporting && a file
Summing && numeric fields
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5. EDITING Records can be changed in the Browse/Edit Windows, or they can be changed using the Replace command
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6. Replace Several Fields
USE project
...
REPLACE date WITH {01/03/2010},;
maxTemp WITH 22, minTemp WITH 16
Further Practice 4 Q.1
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7. Replace All Records or Certain Records
USE formPos Further Practice 1A Q.5
...
REPLACE position WITH RECNO() ALL
USE patient Further Practice 5A Q.5
REPLACE name WITH ‘Mr. ’+name FOR sex =‘M’
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8. Replace Contents of Memo
Let remark be a field of memo type in table student
USE job
REPLACE remark with;
‘Urgent. Delay more than one week!”; ADDITIVE for …
Further Practice 8A Q.2
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9. BLANK
USE project …
BLANK FIELDS minTemp, maxTemp, ; range, aveTemp ALL
Further Practice 4A Q.5
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10. INSERTING New records can be added to a table by using the command APPEND
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11. APPEND Put an additional record at the end of the table.
Open an input window for you to key in data.
If an index is in effect, the record will immediately be moved to its appropriate location.
Usually used interactively.
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12. APPEND BLANK Put an additional record to the end of the table.
If an index is in effect, the record will immediately be moved to its appropriate location.
Usually used in programs.
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13. DELETING
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14. DELETE and PACK Use anyfile go 2
DELETE && The 2nd record is marked for deletion (logically deleted)
PACK && The 2nd record is permanently deleted (physically deleted)
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15. SET DELETE ON SET DELETE ON DELETE ALL LIST && no records will be seen
SET DELETE OFF && default
LIST && all records will be shown
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16. RECALL DELETE ALL && mark all record for deletion
RECALL ALL && unmark all
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17. DELETED() USE student Go 2 DELETE ? DELETED() && output .T. RECALL
? DELETED() && output .F.
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18. DELETED() To browse only records marked for deletion: USE student
BROWSE FOR DELETED() = .T.
or,
BROWSE FOR DELETED()
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19. PACK Physically remove all records marked for deletion.
Cannot be recovered or recalled.
Can you think of a way to recover the physically deleted records?
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20. ZAP Equivalent to DELETE ALL PACK No record is left
The table is empty but not the .DBF file
The .DBF file still holds information about the structure of the table
The .DBF file is the same as that formed by COPY STRUCTURE
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21. COPY STRUCTURE Use f1 COPY STRUCTURE TO f2 USE student
COPY STRUCTURE TO namelist FIELDS class, classno, name
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22. IMPORTING
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23. APPEND FROM a delimited file
USE student
APPEND FROM newstxt TYPE DELIMITED
A delimited file is an ASCII text file in which records are separated from one another by a carriage return and linefeed. Field contents are by default separated by commas.
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24. APPEND FROM a SDF file USE student APPEND FROM newssdf TYPE SDF
SDF stands for System Data Format in FoxPro. An SDF file is an ASCII text file in which records have a fixed length and end with a carriage return and linefeed. Fields are not delimited. Each row of data in the SDF is filled into a record according to the width of each fields
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25. APPEND FROM [a dbf file]
USE complex
APPEND FROM temp
Further Practice 6A Q.5
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26. APPEND FROM an excel file
USE student
APPEND FROM newsxls TYPE XL5
With our machines, Excel files can be imported only if they are of version 5 or earlier.
If the source file is in Excel97 or newer version, first save it in Excel95 version.
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27. EXPORTING
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28. COPY FILE CLOSE ALL COPY FILE anyfile TO newfile
anyfile must not be open.
wildcard characters are not allowed.
The filenames concerned must contain extension if there are any.
Behind the screen: FoxPro call the OS to perform a DOS copy or something similar.
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29. COPY TO USE student COPY TO studback USE f2001
COPY TO f2002 FOR PROMOTED=.T.
COPY TO repeater FIELDS class, classno, name FOR PROMOTED=.F.
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30. Exporting to text files
USE student
COPY TO stcomma.txt TYPE DELIMITED
COPY TO stsdf.txt TYPE SDF
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31. Exporting to Excel 5 USE student COPY TO stxls.xls TYPE XL5
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32. SUMMING
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33. TOTAL
The total command computes totals for numeric fields in the table currently in use.
The results will be stored in a newly created table with the same structure (by default) as the one in use.
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34. TOTAL Records should first be arranged in groups
In this case class should be grouped
USE APStud
TOTAL ON class FIELDS award_cnt, ;
punish_cnt TO result
Further Practice 7A Q.5
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35. TOTAL
For non-numeric fields, values in the first record of each group will be shown (In SQL, that of the last record is shown).
This can be quite misleading in most circumstances.
If only numeric fields and non-numeric fields with consistent value within each group are shown, the result will be more satisfactory.
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36. Backing Up Grandfather-Father-Son Concept
see p
Done by you, not the computer
Use 3 tapes A, B and C
f1 --> f2 --> f3 --> f4
A --> B --> C --> A
grandfa --> father --> son
data in f1 are lost as tape A is overwritten with data in f4
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