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SQL Anywhere 12.0.0 » SQL Anywhere Server - Programming » Python support » Writing Python scripts that use sqlanydb

 

Database type conversion

To control how database types are mapped into Python objects when results are fetched from the database server, conversion callbacks can be registered.

Callbacks are registered using the module level register_converter method. This method is called with the database type as the first parameter and the conversion function as the second parameter. For example, to request that sqlanydb create Decimal objects for data in any column described as having type DT_DECIMAL, you would use the following example:

import sqlanydb
import decimal

def convert_to_decimal(num):
    return decimal.Decimal(num)

sqlanydb.register_converter(sqlanydb.DT_DECIMAL, convert_to_decimal)

Converters may be registered for the following database types:



DT_DATE
DT_TIME
DT_TIMESTAMP
DT_VARCHAR
DT_FIXCHAR
DT_LONGVARCHAR
DT_DOUBLE
DT_FLOAT
DT_DECIMAL
DT_INT
DT_SMALLINT
DT_BINARY
DT_LONGBINARY
DT_TINYINT
DT_BIGINT
DT_UNSINT
DT_UNSSMALLINT
DT_UNSBIGINT
DT_BIT

The following example demonstrates how to convert decimal results to integer resulting in the truncation of any digits after the decimal point. Note that the salary amount displayed when the application is run is an integral value.



import sqlanydb

def convert_to_int(num):
    return int(float(num)) 

sqlanydb.register_converter(sqlanydb.DT_DECIMAL, convert_to_int)

# Create a connection object, then use it to create a cursor
con = sqlanydb.connect( userid="DBA", 
                        password="sql" )
cursor = con.cursor()

# Execute a SQL string
sql = "SELECT * FROM Employees WHERE EmployeeID=105"
cursor.execute(sql)

# Get a cursor description which contains column names
desc = cursor.description
print len(desc)

# Fetch all results from the cursor into a sequence, 
# display the values as column name=value pairs,
# and then close the connection
rowset = cursor.fetchall()
for row in rowset:
    for col in range(len(desc)):
        print "%s=%s" % (desc[col][0], row[col] )
    print
cursor.close()
con.close()