I need to pass a list of values to a MemSQL procedure.
Is there a way of transforming the comma separated integer values from the input string into a table.
MemSQL doesn't yet have something like the python string split function that converts a delimited string into an array of strings. In MemSQL 6.5, the best method would be to do something like this using the locate builtin function.
delimiter //
create or replace procedure insert_split_string(input text, d text) as
declare
position int = 1;
newPosition int = -1;
begin
while newPosition != 0 loop
newPosition = locate(d, input, position);
if newPosition != 0 then
insert into t values(substring(input, position, newPosition - position));
position = newPosition + 1;
end if;
end loop;
-- Add the last delimited element
insert into t values(substring_index(input, d, -1));
end //
delimiter ;
create table t(i int);
call insert_split_string("1,2,3,4,5", ",");
select * from t;
Related
In Flutter, after a Paragraph or TextPainter has laid out it's text, you can get the Rects for the lines (or runs within a line) by calling getBoxesForSelection. If you draw the actual boxes they look something like this:
How do I programmatically get the text within each TextBox?
I wish there were a better way, but this is the only way I have found so far:
// The TextPaint has already been laid out
// select everything
TextSelection selection = TextSelection(baseOffset: 0, extentOffset: textSpan.text.length);
// get a list of TextBoxes (Rects)
List<TextBox> boxes = _textPainter.getBoxesForSelection(selection);
// Loop through each text box
List<String> lineTexts = [];
int start = 0;
int end;
int index = -1;
for (TextBox box in boxes) {
index += 1;
// Uncomment this if you want to only get the whole line of text
// (sometimes a single line may have multiple TextBoxes)
// if (box.left != 0.0)
// continue;
if (index == 0)
continue;
// Go one logical pixel within the box and get the position
// of the character in the string.
end = _textPainter.getPositionForOffset(Offset(box.left + 1, box.top + 1)).offset;
// add the substring to the list of lines
final line = rawText.substring(start, end);
lineTexts.add(line);
start = end;
}
// get the last substring
final extra = rawText.substring(start);
lineTexts.add(extra);
Notes:
To be more rebust, this should check the TextPosition affinity.
This doesn't handle right-to-left text yet.
Update:
If you are getting the text of the whole line, you can use LineMetrics (from TextPainter.computeLineMetrics()) now instead of TextBox. The process would be similar.
I have a string.
string str = "TTFTTFFTTTTF";
How can I break this string and add character ","?
result should be- TTF,TTF,FTT,TTF
You could use String.Join after you've grouped by 3-chars:
var groups = str.Select((c, ix) => new { Char = c, Index = ix })
.GroupBy(x => x.Index / 3)
.Select(g => String.Concat(g.Select(x => x.Char)));
string result = string.Join(",", groups);
Since you're new to programming. That's a LINQ query so you need to add using System.Linq to the top of your code file.
The Select extension method creates an anonymous type containing the char and the index of each char.
GroupBy groups them by the result of index / 3 which is an integer division that truncates decimal places. That's why you create groups of three.
String.Concat creates a string from the 3 characters.
String.Join concatenates them and inserts a comma delimiter between each.
Here is a really simple solution using StringBuilder
var stringBuilder = new StringBuilder();
for (int i = 0; i < str.Length; i += 3)
{
stringBuilder.AppendFormat("{0},", str.Substring(i, 3));
}
stringBuilder.Length -= 1;
str = stringBuilder.ToString();
I'm not sure if the following is better.
stringBuilder.Append(str.Substring(i, 3)).Append(',');
I would suggest to avoid LINQ in this case as it will perform a lot more operations and this is a fairly simple task.
You can use insert
Insert places one string into another. This forms a new string in your C# program. We use the string Insert method to place one string in the middle of another one—or at any other position.
Tip 1:
We can insert one string at any index into another. IndexOf can return a suitable index.
Tip 2:
Insert can be used to concatenate strings. But this is less efficient—concat, as with + is faster.
for(int i=3;i<=str.Length - 1;i+=4)
{
str=str.Insert(i,",");
}
In SAS, I've a variable V containing the following value
V=1996199619961996200120012001
I'ld like to create these 2 variables
V1=19962001 (= different modalities)
V2=42 (= the first modality appears 4 times and the second one appears 2 times)
Any idea ?
Thanks for your help.
Luc
For your first question (if I understand the pattern correctly), you could extract the first four characters and the last four characters:
a = substr(variable, 1,4)
b = substrn(variable,max(1,length(variable)-3),4);
You could then concatenate the two.
c = cats(a,b)
For the second, the COUNT function can be used to count occurrences of a string within a string:
http://support.sas.com/documentation/cdl/en/lefunctionsref/63354/HTML/default/viewer.htm#p02vuhb5ijuirbn1p7azkyianjd8.htm
Hope this helps :)
Make it a bit more general;
%let modeLength = 4;
%let maxOccur = 100; ** in the input **;
%let maxModes = 10; ** in the output **;
Where does a certain occurrence start?;
%macro occurStart(occurNo);
&modeLength.*&occurNo.-%eval(&modeLength.-1)
%mend;
Read the input;
data simplified ;
infile datalines truncover;
input v $%eval(&modeLength.*&maxOccur.).;
Declare output and work variables;
format what $&modeLength..
v1 $%eval(&modeLength.*&maxModes.).
v2 $&maxModes..;
array w {&maxModes.}; ** what **;
array c {&maxModes.}; ** count **;
Discover unique modes and count them;
countW = 0;
do vNo = 1 to length(v)/&modeLength.;
what = substr(v, %occurStart(vNo), &modeLength.);
do wNo = 1 to countW;
if what eq w(wNo) then do;
c(wNo) = c(wNo) + 1;
goto foundIt;
end;
end;
countW = countW + 1;
w(countW) = what;
c(countW) = 1;
foundIt:
end;
Report results in v1 and v2;
do wNo = 1 to countW;
substr(v1, %occurStart(wNo), &modeLength.) = w(wNo);
substr(v2, wNo, 1) = put(c(wNo),1.);
put _N_= v1= v2=;
end;
keep v1 v2;
The data I testes with;
datalines;
1996199619961996200120012001
197019801990
20011996199619961996200120012001
;
run;
I strings in the format of name:key:dataLength:data and these strings can often be chained together. for example "aNum:n:4:9879aBool:b:1:taString:s:2:Hi" this would map to an object something like:
{
aNum: 9879,
aBool: true,
aString: "Hi"
}
I have a method for parsing a string in this format but I'm not sure whether it's use of substring is the most efficient way of pprocessing the string, is there a more efficient way of processing strings in this fashion (repeatedly chopping off the front section):
Map<string, dynamic> fromString(String s){
Map<String, dynamic> _internal = new Map();
int start = 0;
while(start < s.length){
int end;
List<String> parts = new List<String>(); //0 is name, 1 is key, 2 is data length, 3 is data
for(var i = 0; i < 4; i++){
end = i < 3 ? s.indexOf(':') : num.parse(parts[2]);
parts[i] = s.substring(start, end);
start = i < 3 ? end + 1 : end;
}
var tranType = _tranTypesByKey[parts[1]]; //this is just a map to an object which has a function that can convert the data section of the string into an object
_internal[parts[0]] = tranType._fromStr(parts[3]);
}
return _internal;
}
I would try s.split(':') and process the resulting list.
If you do a lot of such operations you should consider creating benchmarks tests, try different techniques and compare them.
If you would still need this line
s = i < 3 ? s.substring(idx + 1) : s.substring(idx);
I would avoid creating a new substring in each iteration but instead just keep track of the next position.
You have to decide how important performance is relative to readability and maintainability of the code.
That said, you should not be cutting off the head of the string repeatedly. That is guaranteed to be inefficient - it'll take time that is quadratic in the number of records in your string, just creating those tail strings.
For parsing each field, you can avoid doing substrings on the length and type fields. For the length field, you can build the number yourself:
int index = ...;
// index points to first digit of length.
int length = 0;
int charCode = source.codeUnitAt(index++);
while (charCode != CHAR_COLON) {
length = 10 * length + charCode - 0x30;
charCode = source.codeUnitAt(index++);
}
// index points to the first character of content.
Since lengths are usually small integers (less than 2<<31), this is likely to be more efficient than creating a substring and calling int.parse.
The type field is a single ASCII character, so you could use codeUnitAt to get its ASCII value instead of creating a single-character string (and then your content interpretation lookup will need to switch on character code instead of character string).
For parsing content, you could pass the source string, start index and length instead of creating a substring. Then the boolean parser can also just read the code unit instead of the singleton character string, the string parser can just make the substring, and the number parser will likely have to make a substring too and call double.parse.
It would be convenient if Dart had a double.parseSubstring(source, [int from = 0, int to]) that could parse a substring as a double without creating the substring.
My String/Query looks like this
insert into Employee Values(1,2,'xxx');
update Employee2 set col1='xxx' where col2='yyy';
select * from Employee3;
I need to take/have TableName alone. Table name won't be constant it will be differed(Employee,Employee2,Employee3) according to DB. I'm new to C# please help me. Thanks in advance.
To get the name of a table from a query (or in this case, a string named 'sql'), try the following:
string sql = "select * from table ";
int index1 = 0;
int index2 = 0;
int currentIndex = 0;
int numSpaces = 0;
char[] chArray = sql.ToCharArray();
foreach (char c in chArray)
{
if (c == ' ')
{
numSpaces++;
if (numSpaces == 3)
index1 = currentIndex;
if (numSpaces == 4)
{
index2 = currentIndex;
break;
}
}
currentIndex++;
}
int length = index2 - index1;
string tableName = sql.Substring(index1, length);
MessageBox.Show(tableName);
Warning - this solution is based on finding the word between the 3rd and 4th space character. This limits you to have a very predictable query structure - more complicated queries may not work with this solution. Your query structure needs to be:
"select column_name1,column_name2,column_name3 from table "
Your query must not have spaces between columns and must have a space at the end aswell. Sorry for the limitations but its the best I can come up with ;)