WHERE clause not working with blank values - sql

In the code below I try to query an Excel file for a particular field "Username" Where there are blanks (= ''). But nothing gets returned to the data adapter.
The WHERE clause will return data for example if I specify a NOT LIKE 'thistext%', but again omits blanks.
Is there some way to better code the clause?
I have read there is an issue if fields are blank and need to be converted to DB NULL (or populated with a value) unsure how to do it.
$connection.ConnectionString = $connectstring
$connection.Open()
$objOleDbCommand.Connection = $connection
$objOleDbCommand.CommandText = "SELECT * FROM [$strSheetName] WHERE [Username] = ''"
$objOleDbAdapter.SelectCommand = $objOleDbCommand
$objOleDbAdapter.Fill($objDataTable)
$objDataTable | Export-Csv "C:\output\MyData_$dateandtime.csv" -NoTypeInformation
$connection.Close()

Try this instead to cover blanks and nulls.
Select * from [$strSheetName] where [Username] = '' OR [USERNAME] IS NULL
Note that this itself is not a powershell issue technically, you might encounter this same issue with other spreadsheets and databases.

Related

How to add to the end of text column through sql?

I am trying to create an sql query that adds a string to the end of the cell. Right now I have this.
$sql = "UPDATE table SET $column1= $column1 + $newstring1, $column2 = $column2 + $newstring2, $column3 = $column3 + $newstring3, WHERE username = $user_username";
The values of $newstring1, $newstring2, and $newstring3 are formatted like "155:2,"
The idea is to add delimiters to each entry so I can easily sort them later. Right now I'm getting a syntax error on my query, but I'm new to php. Is the error because when the database is empty, there is no original variable and therefore I need to INSERT INTO instead of UPDATE, or is the comma in the string itself creating the error and do I need to somehow concatenate it?
I'm more used to C# than PHP so I'm not sure the proper way to format that type of query.

Storing query as a int to check to see if more than one exists

The code is suppose to check my database to see if there are duplicates of activityName existing if that query runs I am suppose to get an error stating that the activity name is taken else if there isn't any activity name in that database with the same name then the activity name would be inserted into the database. Im suppose to execute the query and get the result as an Integer then use the result in the if and else to see if result>0 in the database
var queryCount= 'SELECT COUNT (activityName) FROM dataEntryTb WHERE activityName = "'+an+'" ';
tx.executeSql(queryCount,[]);
if(queryCount > 0){
navigator.notification.alert("Activity Name Taken");
}else{
Not sure what's the issue exactly but it should work fine. You can consider changing it like
var queryCount= "SELECT 1 FROM dataEntryTb WHERE activityName = '" + an + "'";
Again, consider using parameterized query instead of string concatenation to avoid SQL Injection (if an is coming as user input)

Dynamically create sql where condition on textbox entry

I am working on a C# desktop application. I want to create a search functionality. Now the problem is that i am using around 8 textboxes. Different permutations of textboxes could be populated and the resulting 'sql where' condition should only include those textboxes values which are not null. Now one pathetic way is to use a zillion 'if and else' which obviously is laborious. Any other way to do this?
You need just one query with filled WHERE to use all parameters like this
select ...
from ...
WHERE
(firstNameColumn=:firstNameParam or :firstNameParam is null)
AND (lastNameColumn=:lastNameParam or :lastNameParam is null)
AND (...)
I would like to make a point of first checking is the paramtere null, then use it to compare with column values.
Since you are generating query in C#, try old-Chinese approach from Ming period of using default condition where 1=1 just to avoid checking did you already had first condition :)
string query = "select ... from ... join ... on ... where 1=1";
//suposedly you have value of one search box in variable called "item_name"
if(string.IsNullOrWhiteSpace(item_name) == false)
{
query += " and Order_Line.Name ='" + item_name + "'";
}
and so on for other fields.
What you are trying to do in order to avoid ifs is not really a good approach. Look at this:
string query = " select ... where Order_Line.Name = '" + item_name + "'";
What will be the resulting string if item_name is actually null?
EDIT: the resulting query would be
where Order_Line.Name = '' or Order_Line.Name is null
which is not what you want. You want every row if that search field is empty, menaing it shouldn't have anu effect on search. That's why you need condition to see will you include this column in where clause in the first place.

SQL Injection Based on ""=""

I'm new to SQL, so please bear with me (though I'll concede that maybe this is just a programmatic concept that I should have already grasped)...
A reading about possible SQL injection vectors suggested that one potential mode of attack would be to set a username or password field to "or ""=".
An example usage case would be:
uName = getRequestString("UserName");
uPass = getRequestString("UserPass");
sql = "SELECT * FROM Users WHERE Name ='" + uName + "' AND Pass ='" + uPass + "'"
Resulting in the following line of SQL code:
SELECT * FROM Users WHERE Name ="" or ""="" AND Pass ="" or ""=""
The reasoning they gave is that WHERE ""="" always evaluates to true. How and why is this so? I understand how or 1 = 1 evaluates to true, but how does this code evaluate to true?
Your help would be much appreciated!
EDIT:
I think my initial confusion stemmed from reading the double quotes as escapes, instead of empty strings. This should have been obvious, so thanks!
Ignoring the fact that you don't need this special edge case to inject on that query...
The reasoning they gave is that WHERE ''='' always evaluates to true. How and why is this so?
'' is just an empty string constant. So, logically, '' is equal to ''. It's just like saying 1=1, since a constant will always equal itself.
Written out:
SELECT
*
FROM
Users
WHERE
(Name = '' OR '' = '')
AND
(Pass = '' OR '' = '')
Since it is an OR statement, only one of the conditions in each has to be true, BUT it has to be true in both clauses.
You have to always check the varables if included in an SQL statment or as you said, will result in a crash:
if(!string.IsNullOrEmpty(uName) && !string.IsNullOrEmpty(uPass))
{
// SQL STATMENT
}
else
{
// ERROR ONE IS EMPTY
}
also its best to bind those variables to parameters to avoid injection see my answer here on how to do that:
null value exception when entering into database

Generate sql insert script from excel worksheet

I have a large excel worksheet that I want to add to my database.
Can I generate an SQL insert script from this excel worksheet?
I think importing using one of the methods mentioned is ideal if it truly is a large file, but you can use Excel to create insert statements:
="INSERT INTO table_name VALUES('"&A1&"','"&B1&"','"&C1&"')"
In MS SQL you can use:
SET NOCOUNT ON
To forego showing all the '1 row affected' comments. And if you are doing a lot of rows and it errors out, put a GO between statements every once in a while
You can create an appropriate table through management studio interface and insert data into the table like it's shown below. It may take some time depending on the amount of data, but it is very handy.
There is a handy tool which saves a lot of time at
http://tools.perceptus.ca/text-wiz.php?ops=7
You just have to feed in the table name, field names and the data - tab separated and hit Go!
You can use the following excel statement:
="INSERT INTO table_name(`"&$A$1&"`,`"&$B$1&"`,`"&$C$1&"`, `"&$D$1&"`) VALUES('"&SUBSTITUTE(A2, "'", "\'")&"','"&SUBSTITUTE(B2, "'", "\'")&"','"&SUBSTITUTE(C2, "'", "\'")&"', "&D2&");"
This improves upon Hart CO's answer as it takes into account column names and gets rid of compile errors due to quotes in the column. The final column is an example of a numeric value column, without quotes.
Depending on the database, you can export to CSV and then use an import method.
MySQL - http://dev.mysql.com/doc/refman/5.1/en/load-data.html
PostgreSQL - http://www.postgresql.org/docs/8.2/static/sql-copy.html
Use the ConvertFrom-ExcelToSQLInsert from the ImportExcel in the PowerShell Gallery
NAME
ConvertFrom-ExcelToSQLInsert
SYNTAX
ConvertFrom-ExcelToSQLInsert [-TableName] <Object> [-Path] <Object>
[[-WorkSheetname] <Object>] [[-HeaderRow] <int>]
[[-Header] <string[]>] [-NoHeader] [-DataOnly] [<CommonParameters>]
PARAMETERS
-DataOnly
-Header <string[]>
-HeaderRow <int>
-NoHeader
-Path <Object>
-TableName <Object>
-WorkSheetname <Object>
<CommonParameters>
This cmdlet supports the common parameters: Verbose, Debug,
ErrorAction, ErrorVariable, WarningAction, WarningVariable,
OutBuffer, PipelineVariable, and OutVariable. For more information, see
about_CommonParameters (http://go.microsoft.com/fwlink/?LinkID=113216).
ALIASES
None
REMARKS
None
EXAMPLE
ConvertFrom-ExcelToSQLInsert MyTable .\testSQLGen.xlsx
You could use VB to write something that will output to a file row by row adding in the appropriate sql statements around your data. I have done this before.
Here is another tool that works very well...
http://www.convertcsv.com/csv-to-sql.htm
It can take tab separated values and generate an INSERT script. Just copy and paste and in the options under step 2 check the box "First row is column names"
Then scroll down and under step 3, enter your table name in the box "Schema.Table or View Name:"
Pay attention to the delete and create table check boxes as well, and make sure you examine the generated script before running it.
This is the quickest and most reliable way I've found.
You can use the below C# Method to generate the insert scripts using Excel sheet just you need import OfficeOpenXml Package from NuGet Package Manager before executing the method.
public string GenerateSQLInsertScripts() {
var outputQuery = new StringBuilder();
var tableName = "Your Table Name";
if (file != null)
{
var filePath = #"D:\FileName.xsls";
using (OfficeOpenXml.ExcelPackage xlPackage = new OfficeOpenXml.ExcelPackage(new FileInfo(filePath)))
{
var myWorksheet = xlPackage.Workbook.Worksheets.First(); //select the first sheet here
var totalRows = myWorksheet.Dimension.End.Row;
var totalColumns = myWorksheet.Dimension.End.Column;
var columns = new StringBuilder(); //this is your columns
var columnRows = myWorksheet.Cells[1, 1, 1, totalColumns].Select(c => c.Value == null ? string.Empty : c.Value.ToString());
columns.Append("INSERT INTO["+ tableName +"] (");
foreach (var colrow in columnRows)
{
columns.Append("[");
columns.Append(colrow);
columns.Append("]");
columns.Append(",");
}
columns.Length--;
columns.Append(") VALUES (");
for (int rowNum = 2; rowNum <= totalRows; rowNum++) //selet starting row here
{
var dataRows = myWorksheet.Cells[rowNum, 1, rowNum, totalColumns].Select(c => c.Value == null ? string.Empty : c.Value.ToString());
var finalQuery = new StringBuilder();
finalQuery.Append(columns);
foreach (var dataRow in dataRows)
{
finalQuery.Append("'");
finalQuery.Append(dataRow);
finalQuery.Append("'");
finalQuery.Append(",");
}
finalQuery.Length--;
finalQuery.Append(");");
outputQuery.Append(finalQuery);
}
}
}
return outputQuery.ToString();}
Here is a link to an Online automator to convert CSV files to SQL Insert Into statements:
CSV-to-SQL
This query i have generated for inserting the Excel file data into database
In this id and price are numeric values and date field as well. This query summarized all the type which I require It may useful to you as well
="insert into product (product_id,name,date,price) values("&A1&",'" &B1& "','" &C1& "'," &D1& ");"
Id Name Date price
7 Product 7 2017-01-05 15:28:37 200
8 Product 8 2017-01-05 15:28:37 40
9 Product 9 2017-01-05 15:32:31 500
10 Product 10 2017-01-05 15:32:31 30
11 Product 11 2017-01-05 15:32:31 99
12 Product 12 2017-01-05 15:32:31 25
I had to make SQL scripts often and add them to source control and send them to DBA.
I used this ExcelIntoSQL App from windows store https://www.microsoft.com/store/apps/9NH0W51XXQRM
It creates complete script with "CREATE TABLE" and INSERTS.
I have a reliable way to generate SQL inserts batly,and you can modify partial parameters in processing.It helps me a lot in my work, for example, copy one hundreds data to database with incompatible structure and fields count.
IntellIJ DataGrip , the powerful tool i use.
DG can batly receive data from WPS office or MS Excel by column or line.
after copying, DG can export data as SQL inserts.