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author | Jörg Frings-Fürst <debian@jff-webhosting.net> | 2022-12-07 13:17:14 +0100 |
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committer | Jörg Frings-Fürst <debian@jff-webhosting.net> | 2022-12-07 13:17:14 +0100 |
commit | 4875a3dd9b183dcd2256e2abfc4ccf7484c233b4 (patch) | |
tree | 0abbea881ded030851014ffdd60fbf71fead8f65 /html/xbc17.htm | |
parent | daf17154bf13139d9375f48525d19d6aaba08155 (diff) |
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diff --git a/html/xbc17.htm b/html/xbc17.htm deleted file mode 100755 index c1d2c37..0000000 --- a/html/xbc17.htm +++ /dev/null @@ -1,352 +0,0 @@ -<!DOCTYPE HTML PUBLIC> -<HTML> -<TITLE>Xbase DBMS Chapter 17</TITLE> -<BODY BGCOLOR=#FFFFFF> -<H1><p align="center">Index Methods</p></H1> -<p align="center">Chapter Updated 2/12/99</p><hr> - -This chapter lists the xbNdx and xbNtx index methods and provides -examples of how to use them.<br><br> - -There are many methods in the xbNdx and xbNtx classes which are used for -maintaining and updating NDX and NTX files. Fortunately for the -application programmer, most of the complexities of dealing with the -NDX and NTX indices are automatically cared for by the Xbase library.<br><br> - -xbNdx and xbNtx methods which are used by application programs are documented here. -With some exceptions (OpenIndex,CloseIndex and KeyExists) using the index -routines automatically positions and returns the associated record in -the DBF database.<br><br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Xbase xbNdx Index Method List</h3></CAPTION> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Method<TD>Description -<TR><TH ALIGN="LEFT">CheckIndxIntegrity<TD>Checks an index file for integrity -<TR><TH ALIGN="LEFT">CloseIndex<TD>Optional, closes an index. Closing - the DBF file will close any open indexes. -<TR><TH ALIGN="LEFT">CreateIndex<TD>Create an index -<TR><TH ALIGN="LEFT">FindKey<TD>Find a key in an index file -<TR><TH ALIGN="LEFT">GetFirstKey<TD>Get the first key in an index -<TR><TH ALIGN="LEFT">GetLastKey<TD>Get the last key in an index -<TR><TH ALIGN="LEFT">GetNextKey<TD>Get the next key in an index -<TR><TH ALIGN="LEFT">GetPrevKey<TD>Get the previous key in an index -<TR><TH ALIGN="LEFT">KeyExists<TD>Determine if a key exists w/o positioning DBF file -<TR><TH ALIGN="LEFT">OpenIndex<TD>Open an index -<TR><TH ALIGN="LEFT">ReIndex<TD>Rebuilds an index -</TABLE>in -<BR><BR> -<hr> -<h2>Method Definitions</h2> -<hr> - -<h3>Method xbShort xbNdx::CheckIndexIntegrity( xbShort option )</h3> -<h3>Method xbShort xbNtx::CheckIndexIntegrity( xbShort option )</h3><br> - -This method checks an open index for accuracy or file corruption. -If the option is non zero, the method will display informational messages.<br> -<br> -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_LOCK_FAILED<TD>Read lock not successfull -<TR><TH ALIGN="LEFT">XB_NOT_OPEN<TD>File not open -<TR><TH ALIGN="LEFT">XB_INVALID_RECORD<TD>Invalid record number -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek routine error -<TR><TH ALIGN="LEFT">XB_WRITE_ERROR<TD>Write routine error -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/checkndx.cpp">checkndx.cpp</A> for an example -of how to use this method. - -<hr> - -<h3>Method xbShort xbNdx::CloseIndex( VOID )</h3> -<h3>Method xbShort xbNtx::CloseIndex( VOID )</h3><br> - -This method closes an open NDX index. NDX indexes are closed automatically -by the DBF::CloseDatabase routine, so this is an optional method. -Closed indices are not updated by the Xbase routines.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample1.cpp">sample1.cpp</A> for an example -of how to use this method. - -<hr> - -<h3>Method xbShort xbNdx::CreateIndex( char * IndexName, char * KeyExpression, - xbShort Unique, xbShort OverLay )</h3> - -<h3>Method xbShort xbNtx::CreateIndex( char * IndexName, char * KeyExpression, - xbShort Unique, xbShort OverLay )</h3><br> - -This method creates an index. Indices are created as either a -character based index or a numeric based index, depending on the KeyExpression -value.<br><br> -<li><em>Indexname</em> - is the name of the physical index file name. -<li><em>KeyExpression</em> - is the key of the index. -<li><em>Unique</em> - XB_UNIQUE or XB_NOT_UNIQUE -<li><em>Overlay</em> - XB_OVERLAY or XB_DONTOVERLAY<br><br> -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_INVALID_KEY_EXPRESSION<TD>Bad index key expression -<TR><TH ALIGN="LEFT">XB_NOT_OPEN<TD>The database was not open -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> - -<br><br> -Index expressions can be a single field or multiple fields. Assuming a -database has fields LASTNAME and FIRSTNAME, valid index expressions -could be:<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Sample Index Expressions</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Expression<TD>Description -<TR><TH ALIGN="LEFT">"LASTNAME"<TD>Index on LASTNAME only. -<TR><TH ALIGN="LEFT">"LASTNAME+FIRSTNAME"<TD>Index on LASTNAME and FIRSTNAME -<TR><TH ALIGN="LEFT">"LASTNAME-FIRSTNAME"<TD>Index on LASTNAME and FIRSTNAME, -all spaces between the two fields removed. -<TR><TH ALIGN="LEFT">"LASTNAME-','FIRSTNAME"<TD>Index on LASTNAME and -FIRSTNAME, insert a comma between the two values, remove spaces between -the two fields. -</TABLE> -<br><br> -<TABLE BORDER> -<CAPTION ALIGN="TOP"><H3>Allowable Index Expression Operators</H3> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Operator<TD>Key Type<TD>Description -<TR><TH ALIGN="LEFT">+<TD>Character<TD>Concatonate string fields -<TR><TH ALIGN="LEFT">-<TD>Character<TD> -Concatonate string fields, remove trailing spaces -<TR><TH ALIGN="LEFT">'literal'<TD>Character<TD>include literal value -<TR><TH ALIGN="LEFT">"literal"<TD>Character<TD>include literal value -<TR><TH ALIGN="LEFT">+<TD>Numeric<TD>Add two numeric fields togethor -<TR><TH ALIGN="LEFT">-<TD>Numeric<TD>Subtract one numeric field from another -<TR><TH ALIGN="LEFT">*<TD>Numeric<TD>Mulitply two numeric fields togethor -<TR><TH ALIGN="LEFT">/<TD>Numeric<TD>Divide one numeric field into another -<TR><TH ALIGN="LEFT">**<TD>Numeric<TD>Exponential -</TABLE> -<br><br> -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample1.cpp">sample1.cpp</A> for an example -of how to use this method. - -<hr> - -<h3>Method xbShort xbNdx::FindKey( char * SearchValue )</h3> -<h3>Method xbShort xbNdx::FindKey( xbDouble SearchValue )</h3> -<h3>Method xbShort xbNtx::FindKey( char * SearchValue )</h3> -<h3>Method xbShort xbNtx::FindKey( xbDouble SearchValue )</h3><br> - -This method searches the index for key <em>SearchValue</em>. -The routine positions in the index, then positions to the database record -for the key. If the key is not -found, the key value that is the next higher value is returned.<br><br> - -For character keys, the SearchValue should be a null terminated string. -To find an exact match, use a key value which is as long as the key is, -padded on the right with spaces.<br><br> - -For numeric keys, use a xbDouble value for a search value. This is because -all numeric field indices are saved as double values.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_FOUND<TD>The key was found -<TR><TH ALIGN="LEFT">XB_NOT_FOUND<TD>The key was not found -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample5.cpp">sample5.cpp</A> for an example -of how to use this method. - -<hr> - -<h3>Method xbShort xbNdx::GetFirstKey( VOID )</h3> -<h3>Method xbShort xbNtx::GetFirstKey( VOID )</h3><br> - - -This method retrieves the record for the first key in the index.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample5.cpp">sample5.cpp</A> for an example -of how to use this method. - - -<hr> - -<h3>Method xbShort xbNdx::GetLastKey( VOID )</h3> -<h3>Method xbShort xbNtx::GetLastKey( VOID )</h3><br> - -This method retrieves the record for the last key in the index.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample5.cpp">sample5.cpp</A> for an example -of how to use this method. -<hr><h3>Method xbShort xbNdx::GetNextKey( VOID )</h3><br> -This method retrieves the record for the next key in the index. If the -index is not positioned, a call to GetFirstKey is autoamtically executed.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample5.cpp">sample5.cpp</A> for an example -of how to use this method. - - -<hr><h3>Method xbShort xbNdx::GetPrevKey( VOID )</h3> -<hr><h3>Method xbShort xbNtx::GetPrevKey( VOID )</h3><br> - -This method retrieves the record for the previous key in the index. If the -index is not positioned, a call to GetLastKey is autoamtically executed.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> - -<h4>Example Program:</h4> - -See program <A HREF="/XbaseSamples/sample5.cpp">sample5.cpp</A> for an example -of how to use this method. - -<hr> - -<h3>Method xbShort xbNdx::KeyExists( char * SearchValue )</h3> -<h3>Method xbShort xbNdx::KeyExists( xbDouble SearchValue )</h3> -<h3>Method xbShort xbNtx::KeyExists( char * SearchValue )</h3> -<h3>Method xbShort xbNtx::KeyExists( xbDouble SearchValue )</h3><br> - -This method searches the index for the key <em>SearchValue</em>. The routine does not -position the database record for the key. See the reference on FindKey for more -information regarding KeyValue.<br><br> - -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_FOUND<TD>The key was found -<TR><TH ALIGN="LEFT">XB_NOT_FOUND<TD>The key was not found -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> -<h4>Example Program:</h4> -<xmp> -if( xbNdx::KeyExists( "MyKeyValue" )) - cout << "\nKey was found"; -else - cout << "\nKey was not found"; -</xmp> -<hr> -<h3>Method xbShort xbNdx::OpenIndex( char * IndexName )</h3> -<h3>Method xbShort xbNtx::OpenIndex( char * IndexName )</h3><br> -This method opens index <em>IndexName</em> for a given DBF database. An index must be -opened before it will be automatically updated by the database update -routines.<br><br> -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_NO_MEMORY<TD>Memory error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_INVALID_KEY_EXPRESSION<TD>Bad key in index -<TR><TH ALIGN="LEFT">XB_NOT_OPEN<TD>The database was not open -<TR><TH ALIGN="LEFT">XB_SEEK_ERROR<TD>Seek error encountered -<TR><TH ALIGN="LEFT">XB_READ_ERROR<TD>Read error encountered -</TABLE> -<h4>Example Program:</h4> -See program <A HREF="/XbaseSamples/sample1.cpp">sample1.cpp</A> for an example -of how to use this method. -<hr> -<h3>Method xbShort xbNdx::ReIndex( VOID )</h3> -<h3>Method xbShort xbNtx::ReIndex( VOID )</h3><br> -This method rebuilds an index. It is used for optimizing an index, or recreating -a damaged index. If the index is severly damaged (ie; the first 512 bytes are -foobar) then the index must be recreated with the CreateIndex method before -using the ReIndex method.<br><br> -<TABLE BORDER> -<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION><br> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Return Code<TD>Description -<TR><TH ALIGN="LEFT">XB_NO_ERROR<TD>If there is no error -<TR><TH ALIGN="LEFT">XB_OPEN_ERROR<TD>Could not open index file -<TR><TH ALIGN="LEFT">XB_WRITE_ERROR<TD>Error writing data -<TR><TH ALIGN="LEFT">XB_CLOSE_ERROR<TD>Error closing work file -</TABLE> -<h4>Example Program:</h4> -See program <A HREF="/XbaseSamples/reindex.cpp">reindex.cpp</A> for an example -of how to use this method.<br><br> -<hr> -<p><img src="xbase.jpg"><br><hr> -</BODY> -</HTML> |