let r={ email:faker.internet.email() } ;
connection_var.query("insert into users set ?",r, function(err,res){
if(err) throw err;
console.log(res);
} );
connection_var.end();
I wrote this code to insert a fake email addr in already existing database and into the users table just the problem is I am not fully able to understand what and how does the " SET ?" work and how is it relating to r and what if r has more than 1 key-value pairs
? is a placeholder. It gets replaced with all the keys and values in the object passed as the next argument. So if you have
let r = {col1: 1, col2: "abc", col3: 999};
the query will become
insert into users set col1 = 1, col2 = 'abc', col3 = 999
You have 2 separated things here
First is the SET clause (for the insert) that from the documentation:
A SET clause indicates columns explicitly by name, together with the value to assign each one.
link: https://dev.mysql.com/doc/refman/8.0/en/insert.html
The other part is the ? the according to the documentation of mysqljs:
... you can use ? characters as placeholders for values you would like to
have escaped
link: https://github.com/mysqljs/mysql
So, the SET indicates the assignment list of the insert and the ? escapes the values.
Related
I tried invoke bulk update query on mysql using knex raw method.
const ids:number[] = [1,2,3];
const values:string[] = ['apple', null, "orange"]
knex('testtable').raw(
`
UPDATE
TEST_TABLE
SET
COL1 = ELT(FIELD(id, :searchIds), :searchValues),
UPDATE_DATE = NOW()
WHERE ID IN (:searchIds)
`,
{ searchIds: ids, searchValues: values },
);`enter code here`
However, the intended result was not obtained.
This is because values contains a string and null, but theraw method's placeholders do not allow nulls.
Please tell me ,How do I set null to placeholder?
Binding array of values in knex doesn't work like that. SQL has multiple type of arrays, so those cannot be mapped to SQL unambiguous manner.
In docs: https://knexjs.org/#Raw-Bindings is an example how to pass arrays of values to knex.
const myArray = [1,2,3]
knex.raw(
`select * from users where id in (${myArray.map(() => '?').join(',')})`,
[...myArray]
);
In this case using named bindings pretty much impossible (actually named bindings are converted to positional bindings inside knex so there wont be even performance hit because of that).
I Need help for fetch records from table using Go.
My Problem is that i'm writing MySQL query and add another where clause i.e HPhone number, Here HPhone number inserted in data base with format like 999-999-9999.And i passed this HPhone Number in format like 9999999999. which is not matching with correct data base field value. And i used SUBSTRING for add hyphen between numbers but it does not get records but when i passed like 999-999-9999 without SUBSTRING it return records.
Here i demonstrate how i used this.
strQry = `SELECT * from table WHERE Depot = ?`
if HPhone != "" {
strQry += ` AND HPhone = ?`
}
queryArgs := []interface{}{RouteAvailability.Depot}
if HPhone != "" {
queryArgs = append(queryArgs, "SUBSTRING("+HPhone+",1,3)"+"-"+"SUBSTRING("+HPhone+",4,3)"+"-"+"SUBSTRING("+HPhone+",7,4)")
}
Help would be appreciated.
Thanks in advance.
Instead of SUBSTRING you can use REPLACE like so:
queryArgs := []interface{}{RouteAvailability.Depot}
if HPhone != "" {
strQry += ` AND REPLACE(HPhone, '-', '') = ?`
queryArgs = append(queryArgs, HPhone)
}
If possible I would suggest you normalize your data, i.e. decide on a canonical format for a particular data type and everytime your program receives some input that contains that data type you format it into its canonical form, that way you can avoid having to deal with SUBSTRING, or REPLACE, or multiple inconsistent formats etc.
This won't work as you are using prepared statements, and the argument you are building when HPhone is not empty will be used in escaped form - so when executing the query, it won't compare the HPhone values with the computed result of some substring, but with a string containing SUBSTRING(9999...
I have a simple query that I want to pass an array inside which has 5 items. I am using the mysql module so I know it can be done but am not doing the synatx right and therefore getting a syntax error.
Below is the query:
`UPDATE table1 SET table1.col=0 WHERE (table1.col2) IN = (?) AND table1.id=(SELECT ...);`,[arr]
//arr = [1,2,3,4,5];
I have tried:
`UPDATE table1 SET table1.col=0 WHERE (table1.col2) IN = (?,?,?,?,?) AND table1.id=(SELECT ...);`,[arr]`
but I still get a syntax error.
Adding on to Bill Karwin's answer, you can also pass an array to the MySQL query against the '?' placeholder in the same way
WHERE table1.col2 IN (?)
//arr = [1,2,3,4,5];
Passing arr along with the query will convert it to the required SQL string. The mysql module uses the 'SqlString.arrayToList' function from 'sqlstring' module internally for the transformation:
https://github.com/mysqljs/sqlstring/blob/8f193cae10a2208010102fd50f0b61e869e14dcb/lib/SqlString.js#L60
In my case, array inside of array is needed to get this working. Just array variable as parameter passed only first number to sql.
Here is an example: (Notice ids inside of array as the second parameter)
var sql = "SELECT * FROM table WHERE ID IN (?)";
var ids = [1,2,3];
pool.query(sql, [ids], function (err, result, fields) {
if(err) {
console.log(err);
}
else {
console.log(result);
}
}
The syntax of the IN() predicate does not use =.
WHERE (table1.col2) IN = (?,?,?,?,?)
should be
WHERE table1.col2 IN (?,?,?,?,?)
Tip: you can (and should) check syntax yourself in the documentation, so you can get answers more easily than posting to Stack Overflow.
https://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html#function_in
Very similar to this question MySQL Dynamic Query Statement in Python
However what I am looking to do instead of two lists is to use a dictionary
Let's say i have this dictionary
instance_insert = {
# sql column variable value
'instance_id' : 'instnace.id',
'customer_id' : 'customer.id',
'os' : 'instance.platform',
}
And I want to populate a mysql database with an insert statement using sql column as the sql column name and the variable name as the variable that will hold the value that is to be inserted into the mysql table.
Kind of lost because I don't understand exactly what this statement does, but was pulled from the question that I posted where he was using two lists to do what he wanted.
sql = "INSERT INTO instance_info_test VALUES (%s);" % ', '.join('?' for _ in instance_insert)
cur.execute (sql, instance_insert)
Also I would like it to be dynamic in the sense that I can add/remove columns to the dictionary
Before you post, you might want to try searching for something more specific to your question. For instance, when I Googled "python mysqldb insert dictionary", I found a good answer on the first page, at http://mail.python.org/pipermail/tutor/2010-December/080701.html. Relevant part:
Here's what I came up with when I tried to make a generalized version
of the above:
def add_row(cursor, tablename, rowdict):
# XXX tablename not sanitized
# XXX test for allowed keys is case-sensitive
# filter out keys that are not column names
cursor.execute("describe %s" % tablename)
allowed_keys = set(row[0] for row in cursor.fetchall())
keys = allowed_keys.intersection(rowdict)
if len(rowdict) > len(keys):
unknown_keys = set(rowdict) - allowed_keys
print >> sys.stderr, "skipping keys:", ", ".join(unknown_keys)
columns = ", ".join(keys)
values_template = ", ".join(["%s"] * len(keys))
sql = "insert into %s (%s) values (%s)" % (
tablename, columns, values_template)
values = tuple(rowdict[key] for key in keys)
cursor.execute(sql, values)
filename = ...
tablename = ...
db = MySQLdb.connect(...)
cursor = db.cursor()
with open(filename) as instream:
row = json.load(instream)
add_row(cursor, tablename, row)
Peter
If you know your inputs will always be valid (table name is valid, columns are present in the table), and you're not importing from a JSON file as the example is, you can simplify this function. But it'll accomplish what you want to accomplish. While it may initially seem like DictCursor would be helpful, it looks like DictCursor is useful for returning a dictionary of values, but it can't execute from a dict.
I have a database that has stored values in a complicated, serialized array where one component is a string and another is the length of the characters of the string, in this format:
s:8:"test.com"
Where "s" holds the character length of the string in the quotations.
I would like to change the string from "test.com" to "testt.com", and I'm using the following statement in SQL:
UPDATE table SET row=(REPLACE (row, 'test.com','testt.com'))
However, this breaks the script in question, because it doesn't update the character length in the "s" preceding the string where "test.com" is stored.
I was wondering if there is a query I can use that would replace the string, and then also increment the value of this "s" preceding to where the replacement occurs, something like this:
UPDATE table SET row=(REPLACE (row, 's:' number 'test.com','s:' number+1 'testt.com'))
Does anyone know if this kind of query is even possible?
UPDATE table set row = concat('s:',length('testt.com'),':"testt.com"');
If you need to change exact string, then use exact query -
UPDATE table SET row = 's:9:"testt.com"' WHERE row = 's:8:"test.com"';
The string is a "serialized string".
If there are multiple strings to be replaced, it might be easier to create a script to handle this.
In PHP, it goes something like this:
$searchfor = serialize('test.com');
$replaceby = serialize('testt.com');
// strip last semicolon from serialized string
$searchfor = trim($searchfor,';');
$replaceby = trim($replaceby,';');
$query = "UPDATE table SET field = '$replaceby' WHERE field = '$searchfor';";
This way, you can create an exact query string with what you need.
Do fill in the proper code for db connection if necessary.