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Issue-757: added Query update with CASE WHEN capabilities
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‎NewReadMe.md‎

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* New Update and UpdateAsync upgrade: CASE
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** A new feature added to allow developers to programmatically set CASE WHEN when assigning values. Feature includes grouping in sub statements () or
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** to allow condition to point to a column variable instead of a direct paramater value. SQL injection friendly
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** Original Update Statement for multiple records using anonymous objects:
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*** foreach (var item in data)
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*** {
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*** object obj = new
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*** {
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*** MyField = item.Value
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*** };
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*** cnt += await QueryFactory.Query(tableName).Where("Id", item.Id).UpdateAsync(value);
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*** }
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*** return cnt;
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** New Update with select case using multi-level array systems
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** version 1 : allows is equal condition only for now
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** For the Else it will always fill with name of field itself , self assigning.
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** This happens if format is wrong as well.
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** The else protects you fro your field to be set back to NULL
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*** Warning: Limitation is requires , Suggest 200 rows for low number columns,
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*** 25 for higher number columns or clauses.
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var datac = data.Chunk(200); // breaking data up to 200 rows
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//each holds for each update set, which allows multiple value setting as older Update
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List<object[]> cases = [];
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if (datac.Any()) foreach (var d in datac)
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{
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try
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{
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foreach (var item in d) //Build case when statement , standard 3
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{
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cases.Add(["Id", item.Id, item.Value]);
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}
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object obj = new
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{
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MyField= cases.ToArray()
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};
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cases.Clear();
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//if data set is smaller than whole table , best to use in statement to reduce cost
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cnt += await QueryFactory.Query(tableName)
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.WhereIn("Id", d.Select(dd => dd.Id).ToArray())
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.UpdateAsync(value);
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}
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catch { throw; }
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finally { cases.Clear(); }
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}
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else cases.Clear();
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return cnt;
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**standard: Case WHEN x = A then Y... END:
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*** In your cases array the flow is [x,A,Y].
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*** Assignmet value is always last.
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** Available Feaure 1 : While its common to do 3 items for basic, when can extend the criteria with AND and OR
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** It combine, the array column after the orevioud criteria field must be an AND or OR, unless using , () or * explained later
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*** Note: Assignmet value is always last. you can use AND,&&,& or OR,||,|, <>. Not case sensitive.
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*** Case WHEN x = A AND z = B then Y ... END:
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*** In your cases array the flow is [x,A,"AND",z,B,Y]
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*** Case WHEN x = A OR z = B then Y ... END:
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*** Array the flow is [x,A,"OR",z,B,Y]
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** Available Feaure 2 : Subset (). This allows seperating your "And" & "Or" blocks
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*** ex: case when (a = 1 or a = 5) and (b = 7 and c = 2)
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*** This can be placed anywhere before the assignment column or * assignment column,
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*** if you forget to add the ) to close, the engine
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*** will compensate.
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*** Case WHEN (x = A AND z = B) OR J = C then Y ... END:
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*** Array the flow is ["(",x,A,"AND",z,B,")","OR",j,c,Y]
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*** Case WHEN (x = A OR z = B) AND (J = C AND K = D) then Y ... END:
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*** Array the flow is ["(",x,A,"OR",z,B,")","AND","(",j,c,"AND",k,d,")" Y]
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** Available Feaure 3 : To Another Column Field (*). This allows criteria to check if column equals another column (field)
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*** Case WHEN (colx = colb AND colz = colx) then Y ... END:
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*** Array the flow is [,colx,*',colb,"AND",colz,colx, Y]

‎QueryBuilder/BaseQuery.cs‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,8 @@ public abstract partial class BaseQuery<Q> : AbstractQuery where Q : BaseQuery<Q
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private bool orFlag = false;
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private bool notFlag = false;
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public string EngineScope = null;
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public string ToRaw { get; set; }
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public Q SetEngineScope(string engine)
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{

‎QueryBuilder/Compilers/Compiler.cs‎

Lines changed: 149 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -371,7 +371,16 @@ protected virtual SqlResult CompileUpdateQuery(Query query)
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for (var i = 0; i < toUpdate.Columns.Count; i++)
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{
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parts.Add(Wrap(toUpdate.Columns[i]) + " = " + Parameter(ctx, toUpdate.Values[i]));
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var values = toUpdate.Values[i];
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if (values is object[] v && v.Length > 0)
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{
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SetUpCaseWhenUpdatePart(ctx, parts, toUpdate.Columns[i], v);
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}
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else if (values is not Array)
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{
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SetUpDirectUpdatePart(ctx, parts, toUpdate.Columns[i], values);
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}
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else throw new MissingMemberException();
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}
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var sets = string.Join(", ", parts);
@@ -388,6 +397,141 @@ protected virtual SqlResult CompileUpdateQuery(Query query)
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return ctx;
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}
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private void SetUpCaseWhenUpdatePart(SqlResult ctx, List<string> parts, string columnName, object[] value)
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{
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StringBuilder casewrap = new StringBuilder($"{Wrap(columnName)} = ");
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bool hasOne = false;
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foreach (var item in value)
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{
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if (item is object[] i && i.Length >= 3)
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{
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int indent = 0;
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object val = i.Last();
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var subparts = i.Take(i.Length - 1).ToArray();
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int pointer = 0;
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bool substart = true;
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bool start = true;
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bool setasfield = false;
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bool criteriaValue = false;
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var field = string.Empty;
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while (pointer <= (subparts.Length - 1))
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{
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var piece = subparts[pointer].ToString().ToUpperInvariant().Trim();
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if (pointer > 0 && !substart)
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{
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if (!VERB.SpecialChar.Any(s => s == piece) && criteriaValue)
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{
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pointer = subparts.Length;
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break;
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}
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else if (VERB.AndOpertors.Any(s => s == piece))
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{
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casewrap.Append(" ").Append(VERB.And).Append(" ");
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pointer++;
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substart = true;
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continue;
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}
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else if (VERB.OrOpertors.Any(s => s == piece))
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{
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casewrap.Append(" ").Append(VERB.Or).Append(" ");
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pointer++;
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substart = true;
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continue;
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}
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}
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if (!criteriaValue && VERB.AndOrOpertors.Any(s => s == piece))
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{
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pointer = subparts.Length;
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break;
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}
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else if (piece == VERB.StartParenth)
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{
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indent++;
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pointer++; casewrap.Append(VERB.StartParenth);
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continue;
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}
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else if (piece == VERB.EndParenth)
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{
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if (indent > 0)
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{
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indent--;
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casewrap.Append(VERB.EndParenth);
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pointer++;
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continue;
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}
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}
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if (substart && !string.IsNullOrEmpty(field))
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{
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criteriaValue = true;
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}
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if (piece == VERB.PushField && criteriaValue)
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{
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setasfield = true;
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pointer++;
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continue;
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}
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else if (string.IsNullOrEmpty(field))
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{
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field = piece;
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}
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if (substart && criteriaValue && !string.IsNullOrEmpty(field))
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{
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if (!hasOne && start)
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{
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casewrap.Append(VERB.CaseWhen);
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hasOne = true;
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}
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else if (start)
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{
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casewrap.Append(" ").Append(VERB.When);
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}
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casewrap.Append($" {field} = {(setasfield ? subparts[pointer] : Parameter(ctx, subparts[pointer]))}");
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substart = false;
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setasfield = false;
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start = false;
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criteriaValue = false;
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field = string.Empty;
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}
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pointer++;
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}
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if (indent > 0 && hasOne)
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{
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casewrap.Append("".PadLeft(indent, ')'));
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}
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if (hasOne)
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{
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casewrap.Append($" {VERB.Then} {Parameter(ctx, val)}");
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}
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}
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}
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if (!hasOne)
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{
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casewrap.Append($"{Wrap(columnName)}");
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}
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else
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{
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casewrap.Append($" {VERB.Else} {Wrap(columnName)} {VERB.End}");
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}
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parts.Add(casewrap.ToString());
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casewrap.Length = 0;
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}
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private void SetUpDirectUpdatePart(SqlResult ctx, List<string> parts, string columnName, object value)
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{
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parts.Add($"{Wrap(columnName)} = {Parameter(ctx, value)}");
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}
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protected virtual SqlResult CompileInsertQuery(Query query)
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{
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var ctx = new SqlResult(parameterPlaceholder, EscapeCharacter)
@@ -1021,6 +1165,10 @@ public virtual string Parameter(SqlResult ctx, object parameter)
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ctx.Bindings.Add(value);
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return parameterPlaceholder;
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}
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else if (parameter == DBNull.Value)
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{
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parameter = null;
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}
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ctx.Bindings.Add(parameter);
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return parameterPlaceholder;

‎QueryBuilder/Constants.cs‎

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Original file line numberDiff line numberDiff line change
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namespace SqlKata
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{
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public static class VERB
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{
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public const string PushField = "*";
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public const string StartParenth = "(";
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public const string EndParenth = ")";
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public const string And = "AND";
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public const string And2 = "&&";
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public const string And3 = "&";
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public const string Or = "OR";
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public const string Or2 = "||";
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public const string Or3 = "|";
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public const string Or4 = "<>";
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public const string CaseWhen = "CASE WHEN";
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public const string When = "WHEN";
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public const string Else = "ELSE";
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public const string Then = "THEN";
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public const string End = "END";
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public static string[] SpecialChar = [StartParenth, EndParenth, PushField];
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public static string[] AndOrOpertors = [And, And2, And3, Or, Or2, Or3, Or4];
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public static string[] AndOpertors = [And, And2, And3];
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public static string[] OrOpertors = [Or, Or2, Or3, Or4];
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}
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}

‎SqlKata.Execution/QueryFactory.cs‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -859,9 +859,8 @@ private static async Task<IEnumerable<T>> handleIncludesAsync<T>(Query query, IE
859859
internal SqlResult CompileAndLog(Query query)
860860
{
861861
var compiled = this.Compiler.Compile(query);
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query.ToRaw = compiled.RawSql;
863863
this.Logger(compiled);
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return compiled;
866865
}
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