Related
I was working with an application that uses sql server database. I was trying to insert a row into a table as shown below. This table has a primary key 'prodNum'. It's auto-generating key.
When I try to insert a row to the table as shown below,in line intResult = oSglProdTableAdapt.Update(oCableRecDataSet, "ProdTable") I'm getting an exception:
{"Column 'prodNum' is read only."}
I'm not even setting value for 'prodNum' column while creating the datarow as you can see. But the update function trying to write the value for that column also.
I tried to insert using Insert query in sql management studio software. There It's working fine. So I assume that the issue is with my code. Is there anything I'm missing?
' a record does not exist for the new Cable Product
' therefore insert a new data row in the ProdTable table
' clear the DataSet
oCableRecDataSet.Clear()
' create the Data Row
Dim oDR As DataRow = oCableRecDataSet.Tables("ProdTable").NewRow()
' populate the datarow with values
'oDR("ProductIDNum") = 102
oDR("ProductID") = ProductID
oDR("DefinedDate") = DefinedDate
oDR("OperID") = OperID
oDR("CutsizeBased") = CutsizeBased
ProdTable.AddDRofProdTable(oDR)
' add the datarow to the dataset
oCableRecDataSet.Tables("ProdTable").Rows.Add(oDR)
' update the Database with values from Dataset with the Data adapter
intResult = oSglProdTableAdapt.Update(oCableRecDataSet, "ProdTable")
Public Sub AddDRofCableDef(ByRef oDR As DataRow)
oDR("Upper") = m_Upper
oDR("Spec") = m_Spec
oDR("IlUpper") = m_IlUpper
oDR("IlLower") = m_lIlLower
oDR("Spec") = m_Spec
oDR("MeanUpper") = m_MeanUpper
oDR("MeanLower") = m_MeanLower
oDR("MeanUL") = m_MeanUL
oDR("MeanLL") = m_MeanLL
oDR("SUL") = m_SUL
oDR("StartZone") = m_StartZone
End Sub
Stack Trace Follows:
at System.Data.DataRow.set_Item(DataColumn column, Object value) at
System.Data.DataRow.set_Item(String columnName, Object value) at
ACMS.DBCableRecordsCommands.OnRowUpdated(Object sender,
OleDbRowUpdatedEventArgs args) in
D:\Software\clsDBCableRecordsCommands.vb:line 956 at
System.Data.OleDb.OleDbRowUpdatedEventHandler.Invoke(Object sender,
OleDbRowUpdatedEventArgs e) at
System.Data.OleDb.OleDbDataAdapter.OnRowUpdated(RowUpdatedEventArgs
value) at System.Data.Common.DbDataAdapter.Update(DataRow[]
dataRows, DataTableMapping tableMapping) at
System.Data.Common.DbDataAdapter.UpdateFromDataTable(DataTable
dataTable, DataTableMapping tableMapping) at
System.Data.Common.DbDataAdapter.Update(DataSet dataSet, String
srcTable) at
ACMS.DBCableRecordsCommands.insertCableRecord(DBCableRecords Cable) in
D:\Software\clsDBCableRecordsCommands.vb:line 251
UPDATE
One thing I noticed when I checked the generated datarow it has the ProdNum(Primary key) calculated, even though I'm not initializing that value. That may be the reason why sql server is not accepting. How to stop generation of primary key by datarow?
I assume that "oCableRecDataSet" is the name of your DataSet, and the DataSet contains only one Table, so you can try this:
oCableRecDataSet.Tables(0).Columns("produNum").ReadOnly = false
intResult = oSglProdTableAdapt.Update(oCableRecDataSet, "ProdTable")
How do I, reliably, check in SQLite, whether a particular user table exists?
I am not asking for unreliable ways like checking if a "select *" on the table returned an error or not (is this even a good idea?).
The reason is like this:
In my program, I need to create and then populate some tables if they do not exist already.
If they do already exist, I need to update some tables.
Should I take some other path instead to signal that the tables in question have already been created - say for example, by creating/putting/setting a certain flag in my program initialization/settings file on disk or something?
Or does my approach make sense?
I missed that FAQ entry.
Anyway, for future reference, the complete query is:
SELECT name FROM sqlite_master WHERE type='table' AND name='{table_name}';
Where {table_name} is the name of the table to check.
Documentation section for reference: Database File Format. 2.6. Storage Of The SQL Database Schema
This will return a list of tables with the name specified; that is, the cursor will have a count of 0 (does not exist) or a count of 1 (does exist)
If you're using SQLite version 3.3+ you can easily create a table with:
create table if not exists TableName (col1 typ1, ..., colN typN)
In the same way, you can remove a table only if it exists by using:
drop table if exists TableName
A variation would be to use SELECT COUNT(*) instead of SELECT NAME, i.e.
SELECT count(*) FROM sqlite_master WHERE type='table' AND name='table_name';
This will return 0, if the table doesn't exist, 1 if it does. This is probably useful in your programming since a numerical result is quicker / easier to process. The following illustrates how you would do this in Android using SQLiteDatabase, Cursor, rawQuery with parameters.
boolean tableExists(SQLiteDatabase db, String tableName)
{
if (tableName == null || db == null || !db.isOpen())
{
return false;
}
Cursor cursor = db.rawQuery(
"SELECT COUNT(*) FROM sqlite_master WHERE type = ? AND name = ?",
new String[] {"table", tableName}
);
if (!cursor.moveToFirst())
{
cursor.close();
return false;
}
int count = cursor.getInt(0);
cursor.close();
return count > 0;
}
You could try:
SELECT name FROM sqlite_master WHERE name='table_name'
See (7) How do I list all tables/indices contained in an SQLite database in the SQLite FAQ:
SELECT name FROM sqlite_master
WHERE type='table'
ORDER BY name;
Use:
PRAGMA table_info(your_table_name)
If the resulting table is empty then your_table_name doesn't exist.
Documentation:
PRAGMA schema.table_info(table-name);
This pragma returns one row for each column in the named table. Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column. The "pk" column in the result set is zero for columns that are not part of the primary key, and is the index of the column in the primary key for columns that are part of the primary key.
The table named in the table_info pragma can also be a view.
Example output:
cid|name|type|notnull|dflt_value|pk
0|id|INTEGER|0||1
1|json|JSON|0||0
2|name|TEXT|0||0
SQLite table names are case insensitive, but comparison is case sensitive by default. To make this work properly in all cases you need to add COLLATE NOCASE.
SELECT name FROM sqlite_master WHERE type='table' AND name='table_name' COLLATE NOCASE
If you are getting a "table already exists" error, make changes in the SQL string as below:
CREATE table IF NOT EXISTS table_name (para1,para2);
This way you can avoid the exceptions.
If you're using fmdb, I think you can just import FMDatabaseAdditions and use the bool function:
[yourfmdbDatabase tableExists:tableName].
The following code returns 1 if the table exists or 0 if the table does not exist.
SELECT CASE WHEN tbl_name = "name" THEN 1 ELSE 0 END FROM sqlite_master WHERE tbl_name = "name" AND type = "table"
Note that to check whether a table exists in the TEMP database, you must use sqlite_temp_master instead of sqlite_master:
SELECT name FROM sqlite_temp_master WHERE type='table' AND name='table_name';
Here's the function that I used:
Given an SQLDatabase Object = db
public boolean exists(String table) {
try {
db.query("SELECT * FROM " + table);
return true;
} catch (SQLException e) {
return false;
}
}
Use this code:
SELECT name FROM sqlite_master WHERE type='table' AND name='yourTableName';
If the returned array count is equal to 1 it means the table exists. Otherwise it does not exist.
class CPhoenixDatabase():
def __init__(self, dbname):
self.dbname = dbname
self.conn = sqlite3.connect(dbname)
def is_table(self, table_name):
""" This method seems to be working now"""
query = "SELECT name from sqlite_master WHERE type='table' AND name='{" + table_name + "}';"
cursor = self.conn.execute(query)
result = cursor.fetchone()
if result == None:
return False
else:
return True
Note: This is working now on my Mac with Python 3.7.1
You can write the following query to check the table existance.
SELECT name FROM sqlite_master WHERE name='table_name'
Here 'table_name' is your table name what you created. For example
CREATE TABLE IF NOT EXISTS country(country_id INTEGER PRIMARY KEY AUTOINCREMENT, country_code TEXT, country_name TEXT)"
and check
SELECT name FROM sqlite_master WHERE name='country'
Use
SELECT 1 FROM table LIMIT 1;
to prevent all records from being read.
Using a simple SELECT query is - in my opinion - quite reliable. Most of all it can check table existence in many different database types (SQLite / MySQL).
SELECT 1 FROM table;
It makes sense when you can use other reliable mechanism for determining if the query succeeded (for example, you query a database via QSqlQuery in Qt).
The most reliable way I have found in C# right now, using the latest sqlite-net-pcl nuget package (1.5.231) which is using SQLite 3, is as follows:
var result = database.GetTableInfo(tableName);
if ((result == null) || (result.Count == 0))
{
database.CreateTable<T>(CreateFlags.AllImplicit);
}
The function dbExistsTable() from R DBI package simplifies this problem for R programmers. See the example below:
library(DBI)
con <- dbConnect(RSQLite::SQLite(), ":memory:")
# let us check if table iris exists in the database
dbExistsTable(con, "iris")
### returns FALSE
# now let us create the table iris below,
dbCreateTable(con, "iris", iris)
# Again let us check if the table iris exists in the database,
dbExistsTable(con, "iris")
### returns TRUE
I thought I'd put my 2 cents to this discussion, even if it's rather old one..
This query returns scalar 1 if the table exists and 0 otherwise.
select
case when exists
(select 1 from sqlite_master WHERE type='table' and name = 'your_table')
then 1
else 0
end as TableExists
My preferred approach:
SELECT "name" FROM pragma_table_info("table_name") LIMIT 1;
If you get a row result, the table exists. This is better (for me) then checking with sqlite_master, as it will also check attached and temp databases.
This is my code for SQLite Cordova:
get_columnNames('LastUpdate', function (data) {
if (data.length > 0) { // In data you also have columnNames
console.log("Table full");
}
else {
console.log("Table empty");
}
});
And the other one:
function get_columnNames(tableName, callback) {
myDb.transaction(function (transaction) {
var query_exec = "SELECT name, sql FROM sqlite_master WHERE type='table' AND name ='" + tableName + "'";
transaction.executeSql(query_exec, [], function (tx, results) {
var columnNames = [];
var len = results.rows.length;
if (len>0){
var columnParts = results.rows.item(0).sql.replace(/^[^\(]+\(([^\)]+)\)/g, '$1').split(','); ///// RegEx
for (i in columnParts) {
if (typeof columnParts[i] === 'string')
columnNames.push(columnParts[i].split(" ")[0]);
};
callback(columnNames);
}
else callback(columnNames);
});
});
}
Table exists or not in database in swift
func tableExists(_ tableName:String) -> Bool {
sqlStatement = "SELECT name FROM sqlite_master WHERE type='table' AND name='\(tableName)'"
if sqlite3_prepare_v2(database, sqlStatement,-1, &compiledStatement, nil) == SQLITE_OK {
if sqlite3_step(compiledStatement) == SQLITE_ROW {
return true
}
else {
return false
}
}
else {
return false
}
sqlite3_finalize(compiledStatement)
}
c++ function checks db and all attached databases for existance of table and (optionally) column.
bool exists(sqlite3 *db, string tbl, string col="1")
{
sqlite3_stmt *stmt;
bool b = sqlite3_prepare_v2(db, ("select "+col+" from "+tbl).c_str(),
-1, &stmt, 0) == SQLITE_OK;
sqlite3_finalize(stmt);
return b;
}
Edit: Recently discovered the sqlite3_table_column_metadata function. Hence
bool exists(sqlite3* db,const char *tbl,const char *col=0)
{return sqlite3_table_column_metadata(db,0,tbl,col,0,0,0,0,0)==SQLITE_OK;}
You can also use db metadata to check if the table exists.
DatabaseMetaData md = connection.getMetaData();
ResultSet resultSet = md.getTables(null, null, tableName, null);
if (resultSet.next()) {
return true;
}
If you are running it with the python file and using sqlite3 obviously. Open command prompt or bash whatever you are using use
python3 file_name.py first in which your sql code is written.
Then Run sqlite3 file_name.db.
.table this command will give tables if they exist.
I wanted to add on Diego Vélez answer regarding the PRAGMA statement.
From https://sqlite.org/pragma.html we get some useful functions that can can return information about our database.
Here I quote the following:
For example, information about the columns in an index can be read using the index_info pragma as follows:
PRAGMA index_info('idx52');
Or, the same content can be read using:
SELECT * FROM pragma_index_info('idx52');
The advantage of the table-valued function format is that the query can return just a subset of the PRAGMA columns, can include a WHERE clause, can use aggregate functions, and the table-valued function can be just one of several data sources in a join...
Diego's answer gave PRAGMA table_info(table_name) like an option, but this won't be of much use in your other queries.
So, to answer the OPs question and to improve Diegos answer, you can do
SELECT * FROM pragma_table_info('table_name');
or even better,
SELECT name FROM pragma_table_list('table_name');
if you want to mimic PoorLuzers top-voted answer.
If you deal with Big Table, I made a simple hack with Python and Sqlite and you can make the similar idea with any other language
Step 1: Don't use (if not exists) in your create table command
you may know that this if you run this command that will have an exception if you already created the table before, and want to create it again, but this will lead us to the 2nd step.
Step 2: use try and except (or try and catch for other languages) to handle the last exception
here if you didn't create the table before, the try case will continue, but if you already did, you can put do your process at except case and you will know that you already created the table.
Here is the code:
def create_table():
con = sqlite3.connect("lists.db")
cur = con.cursor()
try:
cur.execute('''CREATE TABLE UNSELECTED(
ID INTEGER PRIMARY KEY)''')
print('the table is created Now')
except sqlite3.OperationalError:
print('you already created the table before')
con.commit()
cur.close()
You can use a simple way, i use this method in C# and Xamarin,
public class LoginService : ILoginService
{
private SQLiteConnection dbconn;
}
in login service class, i have many methods for acces to the data in sqlite, i stored the data into a table, and the login page
it only shows when the user is not logged in.
for this purpose I only need to know if the table exists, in this case if it exists it is because it has data
public int ExisteSesion()
{
var rs = dbconn.GetTableInfo("Sesion");
return rs.Count;
}
if the table does not exist, it only returns a 0, if the table exists it is because it has data and it returns the total number of rows it has.
In the model I have specified the name that the table must receive to ensure its correct operation.
[Table("Sesion")]
public class Sesion
{
[PrimaryKey]
public int Id { get; set; }
public string Token { get; set; }
public string Usuario { get; set; }
}
Look into the "try - throw - catch" construct in C++. Most other programming languages have a similar construct for handling errors.
I inherited a project and I'm running into a SQL error that I'm not sure how to fix.
On an eCommerce site, the code is inserting order shipping info into another database table.
Here's the code that is inserting the info into the table:
string sql = "INSERT INTO AC_Shipping_Addresses
(pk_OrderID, FullName, Company, Address1, Address2, City, Province, PostalCode, CountryCode, Phone, Email, ShipMethod, Charge_Freight, Charge_Subtotal)
VALUES (" + _Order.OrderNumber;
sql += ", '" + _Order.Shipments[0].ShipToFullName.Replace("'", "''") + "'";
if (_Order.Shipments[0].ShipToCompany == "")
{
sql += ", '" + _Order.Shipments[0].ShipToFullName.Replace("'", "''") + "'";
}
else
{
sql += ", '" + _Order.Shipments[0].ShipToCompany.Replace("'", "''") + "'";
}
sql += ", '" + _Order.Shipments[0].Address.Address1.Replace("'", "''") + "'";
sql += ", '" + _Order.Shipments[0].Address.Address2.Replace("'", "''") + "'";
sql += ", '" + _Order.Shipments[0].Address.City.Replace("'", "''") + "'";
sql += ", '" + _Order.Shipments[0].Address.Province.Replace("'", "''") + "'";
sql += ", '" + _Order.Shipments[0].Address.PostalCode.Replace("'", "''") + "'";
sql += ", '" + _Order.Shipments[0].Address.Country.Name.Replace("'", "''") + "'";
sql += ", '" + _Order.Shipments[0].Address.Phone.Replace("'", "''") + "'";
if (_Order.Shipments[0].ShipToEmail == "")
{
sql += ",'" + _Order.BillToEmail.Replace("'", "''") + "'";
}
else
{
sql += ",'" + _Order.Shipments[0].ShipToEmail.Replace("'", "''") + "'";
}
sql += ", '" + _Order.Shipments[0].ShipMethod.Name.Replace("'", "''") + "'";
sql += ", " + shippingAmount;
sql += ", " + _Order.ProductSubtotal.ToString() + ")";
bll.dbUpdate(sql);
It is working correctly, but it is also outputting the following SQL error:
Violation of PRIMARY KEY constraint 'PK_AC_Shipping_Addresses'. Cannot insert
duplicate key in object 'dbo.AC_Shipping_Addresses'. The duplicate key value
is (165863).
From reading similar questions, it seems that I should declare the ID in the statement.
Is that correct? How would I adjust the code to fix this issue?
I was getting the same error on a restored database when I tried to insert a new record using the EntityFramework. It turned out that the Indentity/Seed was screwing things up.
Using a reseed command fixed it.
DBCC CHECKIDENT ('[Prices]', RESEED, 4747030);GO
I'm pretty sure pk_OrderID is the PK of AC_Shipping_Addresses
And you are trying to insert a duplicate via the _Order.OrderNumber?
Do a
select * from AC_Shipping_Addresses where pk_OrderID = 165863;
or select count(*) ....
Pretty sure you will get a row returned.
It is telling you that you are already using pk_OrderID = 165863 and cannot have another row with that value.
if you want to not insert if there is a row
insert into table (pk, value)
select 11 as pk, 'val' as value
where not exists (select 1 from table where pk = 11)
What is the value you're passing to the primary key (presumably "pk_OrderID")? You can set it up to auto increment, and then there should never be a problem with duplicating the value - the DB will take care of that. If you need to specify a value yourself, you'll need to write code to determine what the max value for that field is, and then increment that.
If you have a column named "ID" or such that is not shown in the query, that's fine as long as it is set up to autoincrement - but it's probably not, or you shouldn't get that err msg. Also, you would be better off writing an easier-on-the-eye query and using params. As the lad of nine years hence inferred, you're leaving your database open to SQL injection attacks if you simply plop in user-entered values. For example, you could have a method like this:
internal static int GetItemIDForUnitAndItemCode(string qry, string unit, string itemCode)
{
int itemId;
using (SqlConnection sqlConn = new SqlConnection(ReportRunnerConstsAndUtils.CPSConnStr))
{
using (SqlCommand cmd = new SqlCommand(qry, sqlConn))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.Add("#Unit", SqlDbType.VarChar, 25).Value = unit;
cmd.Parameters.Add("#ItemCode", SqlDbType.VarChar, 25).Value = itemCode;
sqlConn.Open();
itemId = Convert.ToInt32(cmd.ExecuteScalar());
}
}
return itemId;
}
...that is called like so:
int itemId = SQLDBHelper.GetItemIDForUnitAndItemCode(GetItemIDForUnitAndItemCodeQuery, _unit, itemCode);
You don't have to, but I store the query separately:
public static readonly String GetItemIDForUnitAndItemCodeQuery = "SELECT PoisonToe FROM Platypi WHERE Unit = #Unit AND ItemCode = #ItemCode";
You can verify that you're not about to insert an already-existing value by (pseudocode):
bool alreadyExists = IDAlreadyExists(query, value) > 0;
The query is something like "SELECT COUNT FROM TABLE WHERE BLA = #CANDIDATEIDVAL" and the value is the ID you're potentially about to insert:
if (alreadyExists) // keep inc'ing and checking until false, then use that id value
Justin wants to know if this will work:
string exists = "SELECT 1 from AC_Shipping_Addresses where pk_OrderID = " _Order.OrderNumber; if (exists > 0)...
What seems would work to me is:
string existsQuery = string.format("SELECT 1 from AC_Shipping_Addresses where pk_OrderID = {0}", _Order.OrderNumber);
// Or, better yet:
string existsQuery = "SELECT COUNT(*) from AC_Shipping_Addresses where pk_OrderID = #OrderNumber";
// Now run that query after applying a value to the OrderNumber query param (use code similar to that above); then, if the result is > 0, there is such a record.
To prevent inserting a record that exist already. I'd check if the ID value exists in the database. For the example of a Table created with an IDENTITY PRIMARY KEY:
CREATE TABLE [dbo].[Persons] (
ID INT IDENTITY(1,1) PRIMARY KEY,
LastName VARCHAR(40) NOT NULL,
FirstName VARCHAR(40)
);
When JANE DOE and JOE BROWN already exist in the database.
SET IDENTITY_INSERT [dbo].[Persons] OFF;
INSERT INTO [dbo].[Persons] (FirstName,LastName)
VALUES ('JANE','DOE');
INSERT INTO Persons (FirstName,LastName)
VALUES ('JOE','BROWN');
DATABASE OUTPUT of TABLE [dbo].[Persons] will be:
ID LastName FirstName
1 DOE Jane
2 BROWN JOE
I'd check if i should update an existing record or insert a new one. As the following JAVA example:
int NewID = 1;
boolean IdAlreadyExist = false;
// Using SQL database connection
// STEP 1: Set property
System.setProperty("java.net.preferIPv4Stack", "true");
// STEP 2: Register JDBC driver
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
// STEP 3: Open a connection
try (Connection conn1 = DriverManager.getConnection(DB_URL, USER,pwd) {
conn1.setAutoCommit(true);
String Select = "select * from Persons where ID = " + ID;
Statement st1 = conn1.createStatement();
ResultSet rs1 = st1.executeQuery(Select);
// iterate through the java resultset
while (rs1.next()) {
int ID = rs1.getInt("ID");
if (NewID==ID) {
IdAlreadyExist = true;
}
}
conn1.close();
} catch (SQLException e1) {
System.out.println(e1);
}
if (IdAlreadyExist==false) {
//Insert new record code here
} else {
//Update existing record code here
}
Not OP's answer but as this was the first question that popped up for me in google, Id also like to add that users searching for this might need to reseed their table, which was the case for me
DBCC CHECKIDENT(tablename)
There could be several things causing this and it somewhat depends on what you have set up in your database.
First, you could be using a PK in the table that is also an FK to another table making the relationship 1-1. IN this case you may need to do an update rather than an insert. If you really can have only one address record for an order this may be what is happening.
Next you could be using some sort of manual process to determine the id ahead of time. The trouble with those manual processes is that they can create race conditions where two records gab the same last id and increment it by one and then the second one can;t insert.
Third, you query as it is sent to the database may be creating two records. To determine if this is the case, Run Profiler to see exactly what SQL code you are sending and if ti is a select instead of a values clause, then run the select and see if you have due to the joins gotten some records to be duplicated. IN any even when you are creating code on the fly like this the first troubleshooting step is ALWAYS to run Profiler and see if what got sent was what you expected to be sent.
Make sure if your table doesn't already have rows whose Primary Key values are same as the the Primary Key Id in your Query.
I'am very new with text datatype in SQL Server 2008
I created table:
CREATE TABLE sample(id int identity,name varchar(20),Yell_Your_self text)
but I am facing problem with inserting
insert into sample values('ganesh','welcome to india')
insert into sample values('ganesh','welcome to india's largest temple')
First statement is working fine but how to execute second statement?
Try this one -
IF OBJECT_ID(N'dbo.sample') IS NOT NULL
DROP TABLE dbo.[sample]
CREATE TABLE dbo.[sample]
(
id INT IDENTITY(1,1) PRIMARY KEY
, name VARCHAR(20)
, Yell_Your_self VARCHAR(2000)
)
INSERT INTO dbo.[sample]
VALUES
('ganesh', 'welcome to india'),
('ganesh', 'welcome to india''s largest temple')
Update3:
public int get(string val1,string val2)
{
using(SqlConnection con = new SqlConnection(connectionString))
{
con.Open();
int i = 0;
using (SqlCommand cmd = new SqlCommand("INSERT INTO dbo.sample (name, Yell_Your_self) VALUES(#val1, #val2)", con))
{
cmd.Parameters.AddWithValue("#val1", val1);
cmd.Parameters.AddWithValue("#val2", val2);
i = cmd.ExecuteNonQuery();
}
con.Close();
return i;
}
}
Likely throwing an error on the apostrophe in the india's
insert into sample values('ganesh','welcome to india''s largest temple')
The issue is that you have a single quote in the string, and a single quote is a string delimiter in SQL.
Try:
INSERT INTO sample VALUES ('ganesh','welcome to india''s largest temple')
As you are already aware that the trouble SQL is facing is to escape an apostrophy in query, which is fixed i guess. To answer your second question about how to pass value from front end like C#, parametrized query is one of the good approach. As an alternative you can go with this one also which involves string manipulations to prepare a query:
public int get(string val1,string val2)
{
string temp = string.Concat(val1,"," + val2); // concatenate all your params
temp = temp.replace("'","''").replace(",","','"); // replace any single qoute with escaped single quote
string s="insert into sample values('" + temp + "')"; // append altered string in query
SqlCommand cmd = new SqlCommand(s,con);
con.Open();
int i = cmd.ExecuteNonQuery();
con.Close();
return i;
}
Hope it helps!
try this with passing dynamic value
insert into sample values(#name, N''' + #Yell_Your_self text + ''' )
I use Sql server 2008 to store my data,and the table structure like that
index float not null,
type int not null,
value int not null,
and the (index,type) is unique.there are not two datas has the same index and the same type.
So when I insert the data to the table, I have to check the (index,type) pair whether in the table already, if it exists I use update statement, otherwise, I insert it directly.but I think this is not a efficient way,because:
Most of the data' index-type pair is not existed int the table.so the select operation is waste, especially the table is huge.
When I use C# or other CLR language to insert the data, I can't use batch copy or batch insert.
is there any way to overwrite the data directly without check whether it is existed in the table?
If you want to update OR insert the data, you need to use merge:
merge MyTable t using (select #index index, #type type, #value value) s on
t.index = s.index
and t.type = s.type
when not matched insert (index, type value) values (s.index, s.type, s.value)
when matched update set value = s.value;
This will look at your values and take the appropriate action.
To do this in C#, you have to use the traditional SqlClient:
SqlConnection conn = new SqlConnection("Data Source=dbserver;Initial Catalog=dbname;Integrated Security=SSPI;");
SqlCommand comm = new SqlCommand();
conn.Open();
comm.Connection = conn;
//Add in your values here
comm.Parameters.AddWithValue("#index", index);
comm.Parameters.AddWithValue("#type", type);
comm.Parameters.AddWithValue("#value", value);
comm.CommandText =
"merge MyTable t using (select #index index, #type type, #value value) s on " +
"t.index = s.index and t.type = s.type " +
"when not matched insert (index, type value) values (s.index, s.type, s.value) " +
"when matched update set value = s.value;"
comm.ExecuteNonQuery();
comm.Dispose();
conn.Close();
conn.Dispose();
You should make (index, type) into a composite primary key (aka compound key).
This would ensure that the table can only even have unique pairs of these (I am assuming the table does not have a primary key already).
If the table does have a primary key, you can add a UNIQUE constraint onto those columns with similar effect.
Once defined, this means that any attempt to insert a duplicate pair would fail.
Other answers recommend constraints. Creating constraints just means you will be executing insert statements that trigger errors. The next step (after having created the constraints) is something like INSERT ON DUPLICATE KEY UPDATE, which apparently does have an Sql Server equivalent.