python mysql error in query

问题

I want to generate a dynamic table:

columnames=[element[0] for element in bufferdata['data'] ]
for index,element in enumerate(columnames):
        columnames[index]=re.sub("[(%./)-]","",element)
    tuple(columnames)
    querycreatetable='''CREATE TABLE test (ID INT AUTO_INCREMENT,name VARCHAR(50),symbol VARCHAR(10),sector VARCHAR(50),
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,%s FLOAT,
                                           %s FLOAT,%s FLOAT,%s FLOAT
                                           ) 
                        '''
    try:
        self.cursor.execute(querycreatetable,columnames)
    except MySQLdb.ProgrammingError, e:
        try:
            print "MySQL Error [%d]: %s" % (e.args[0], e.args[1])
        except IndexError:
            print "MySQL Error: %s" % str(e)

but i receive this error: MySQL Error [1064]: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''SALES in millions' FLOAT,'Earnings per share' FLOAT,'PE Ratio TTM' FLOAT,'PE Hi' at line 2

does anyone see where the problem is?

回答1:

firstly, as told here : Check for valid SQL column name

SQL identifiers and key words must begin with a letter (a-z, but also letters with diacritical marks and non-Latin letters) or an underscore (_). Subsequent characters in an identifier or key word can be letters, underscores, digits (0-9), or dollar signs ($). Note that dollar signs are not allowed in identifiers according to the letter of the SQL standard, so their use might render applications less portable

It comes from PostGre doc, but because PostGre is very close to the "ideal" SQL syntax, it might be the same for mysql... So no parenthesis into column names, no spaces...

And secondly, Column names are not strings :

The following syntax is valid:

CREATE TABLE (test VARCHAR(100) NOT NULL, ...)

And the following one is invalid and will throw a syntax error:

CREATE TABLE ('test' VARCHAR(100) NOT NULL, ...)

When you use the '%s' modifier, it parses data as STRING. so it surrounds it with quotes, which is invalid...

So for create your table, I suggest a "for loop" which validate data (with regexpr), and symply add it to the string:

import re
# ...
query = "CREATE TABLE test (ID INT AUTO_INCREMENT,name VARCHAR(50)"
for c in columnames:
        if (re.search(r"^[A-Za-z][A-Za-z0-9_]*$", c) query += c + ", FLOAT" #this regex validate string if  it begins with alphabetic char (upper or lower case), and if the others characters are alphanumeric, or are underscores
        else raise SyntaxError("Invalid Column name!!") #If not, we raise a syntax error
query += ");"

And then you can create your table :)

回答2:

here the solution

columnames=[element[0] for element in bufferdata['data'] ]
    queryCT="CREATE TABLE test (ID INT AUTO_INCREMENT primary key,name VARCHAR(50),symbol VARCHAR(10),sector VARCHAR(50)"
    for c in columnames:
        queryCT += "," + str(re.sub("[(%./)-]","",c)).replace(' ','') + " FLOAT"  
    queryCT += ")"

    print queryCT
    try:
        self.cursor.execute(queryCT)
    except MySQLdb.ProgrammingError, e:
        try:
            print "MySQL Error [%d]: %s" % (e.args[0], e.args[1])
        except IndexError:
            print "MySQL Error: %s" % str(e)

The idea to bild the query string and then to send it to cursor.execute works great.

来源：https://stackoverflow.com/questions/36355630/python-mysql-error-in-query

标签

python

mysql

sql

mysql-python