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Database Abstraction Layer for PHP

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v5:userguide:portable_sql [2016/02/27 18:39] – mnewnhamv5:userguide:portable_sql [2016/03/13 23:52] – [Inserting Records] mnewnham
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 ==== Fetch Modes Within Select Statements ==== ==== Fetch Modes Within Select Statements ====
  
-PHP allows you to retrieve database records as arrays. You can choose to have the arrays indexed by field name or number. However different low-level PHP database drivers are inconsistent in their indexing efforts. ADOdb allows you to determine your prefered mode. You set this by setting the variable [[v5:reference:connection:adodb_fetch_mode|$ADODB_FETCH_MODE]] to either of the constants:+PHP allows you to retrieve database records as arrays. You can choose to have the arrays indexed by field name or number. However different low-level PHP database drivers are inconsistent in their indexing efforts. ADOdb allows you to determine your prefered mode. You set this by setting the variable [[v5:reference:adodb_fetch_mode|$ADODB_FETCH_MODE]] to either of the constants:
   * ADODB_FETCH_NUM (for numeric indexes)   * ADODB_FETCH_NUM (for numeric indexes)
   * ADODB_FETCH_ASSOC (using field names as an associative index).   * ADODB_FETCH_ASSOC (using field names as an associative index).
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 Another problem with SELECTs is that some databases do not return the number of rows retrieved from a select statement. This is because the highest performance databases will return records to you even before the last record has been found. Another problem with SELECTs is that some databases do not return the number of rows retrieved from a select statement. This is because the highest performance databases will return records to you even before the last record has been found.
  
-In ADOdb, [[v5:reference:recordcount]] returns the number of rows returned, or will emulate it by buffering the rows and returning the count after all rows have been returned. This can be disabled for performance reasons when retrieving large recordsets by setting the global variable [[v5:reference:connection:adodb_countrecs|$ADODB_COUNTRECS]] = false. This variable is checked every time a query is executed, so you can selectively choose which recordsets to count.+In ADOdb, [[v5:reference:connection:recordcount|recordCount()]] returns the number of rows returned, or will emulate it by buffering the rows and returning the count after all rows have been returned. This can be disabled for performance reasons when retrieving large recordsets by setting the global variable [[v5:reference:adodb_countrecs|$ADODB_COUNTRECS]] = false. This variable is checked every time a query is executed, so you can selectively choose which recordsets to count.
  
 If you prefer to set ''$ADODB_COUNTRECS'' = false, ADOdb still has the [[v5:reference:connection:po_recordcount|po_recordCount()]] function. This will return the number of rows, or if it is not found, it will return an estimate using ''SELECT COUNT(*)'': If you prefer to set ''$ADODB_COUNTRECS'' = false, ADOdb still has the [[v5:reference:connection:po_recordcount|po_recordCount()]] function. This will return the number of rows, or if it is not found, it will return an estimate using ''SELECT COUNT(*)'':
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 ===== Inserting Records ===== ===== Inserting Records =====
  
-When you create records, you need to generate unique id's for each record. There are two common techniques: (1) auto-incrementing columns and (2) sequences.+When you create records, you need to generate unique id's for each record. There are two common techniques:  
 +  * Auto-increment columns 
 +  * Sequences
  
-Auto-incrementing columns are not supported by some databases, so for portability, you have little choice but to use sequences. Sequences are special functions that return a unique incrementing number every time you call it, suitable to be used as database keys. In ADOdb, we use the [[v5:reference:connection:genid|genId()]] function. It has takes a parameter, the sequence name. Different tables can have different sequences.+Auto-increment columns are not supported by some databases, so for portability, you have little choice but to use sequences. Sequences are special functions that return a unique incrementing number every time you call it, suitable to be used as database keys. In ADOdb, we use the [[v5:reference:connection:genid|genId()]] function. It has takes a parameter, the sequence name.  
 + 
 +Different tables can have different sequences.
  
 <code php> <code php>
 $id = $connection->GenID('sequence_name'); $id = $connection->GenID('sequence_name');
 $connection->Execute("insert into table (id, firstname, lastname)  $connection->Execute("insert into table (id, firstname, lastname) 
-    values ($id, $firstname, $lastname)");+          values ($id, $firstname, $lastname)");
  
 </code> </code>
-For databases that do not support sequences natively, ADOdb emulates sequences by creating a table for every sequence.+For databases that do not provide native support for sequence, ADOdb provides emulation by creating a table for every sequence.
  
 ===== Binding ===== ===== Binding =====
v5/userguide/portable_sql.txt · Last modified: 2020/12/30 21:32 by peterdd