使用 pyhon 的动态 sql 查询形成

Question

I am new to the python and want to form SQL query dynamically in python.so tried below sample code:

empId = 12

query = ''' select  name, ''' +
if empId > 10:
    '''basic_salary'''
else:
    ''' bonus'''
+ ''' from employee '''

print(query)

but, getting syntax error. does anyone knows how to form dynamic query in python.

Answer 1

You need to indicate that the assignment to query continues on the next line, which you can do with a \ at the end of the line. Also, you need to write the if statement as an inline if expression as you can't have an if statement in the middle of an assignment statement:

empId = 12

query = ''' select  name, ''' + \
        ('''basic_salary''' if empId > 10 else ''' bonus''') + \
        ''' from employee '''

print(query)

Output:

select  name, basic_salary from employee 

If you have multiple conditions, you can just add to query in the conditions. For example:

empId = 6

query = 'select name, '
if empId > 10:
    query += 'basic_salary'
elif empId > 5:
    query += 'benefits'
else:
    query += 'bonus'
query += ' from employee'

print(query)

Output

select name, benefits from employee

Answer 2

#dynamic sql query formation using python #This is for PostgresSQL you can use this for other queries as well:

def updateQuery(self,tableName,setFields,setValues,whereFields,whereValues): print("Generating update query started")

querySetfields = None
queryWhereFields = None

# Loop for set fields
for i in range(len(setFields)):
    if querySetfields is None:
        querySetfields=setFields[i]+"='"+setValues[i]+"'"
    else:
        querySetfields=querySetfields+","+setFields[i]+"='"+setValues[i]+"'"

# Loop for whereFields
for i in range(len(whereFields)):
    if queryWhereFields is None:
        queryWhereFields=whereFields[i]+"='"+whereValues[i]+"'"
    else:
        queryWhereFields=queryWhereFields+","+whereFields[i]+"='"+whereValues[i]+"'"

#Form the complete update query
query="UPDATE "+tableName+" SET "+querySetfields+" WHERE "+queryWhereFields

print("Generating update query completed")

return query

print(updateQuery(None,"EMPLOYEE_DETAILS",["EMPI_ID","EMP_LANID","EMP_NAME","EMP_EMAIL"],["A","B","C"],["EMPI_ID","EMP_LANID"],["X","Y","Z"]))