CODEWITHSUNDEEP
c#sql.netregex
Carven
Carven

Reputation: 15660

How to select column names and tables of an SQL using regex?

I have an SQL string that looks something like this:

SELECT
    USER."ID", USER."NAME", USER."BIRTH",USER."GENDER",
    PACKAGE."type"
    PACKAGE."code"
FROM
    "DBNAME"."USER" USER,
    "DBNAME2"."PACKAGE" PACKAGE
WHERE
    USER."PACKAGE_ID" = PACKAGE."ID"
ORDER BY
    USER."NAME";

How should I write my regular expression in C# to extract all the column names between the SELECT and FROM keywords, and then the table names in the FROM clause?

The expected output should find these so that I can put them into List to loop through:

ColumnsList:

USER."ID"
USER."NAME"
USER."BIRTH"
USER."GENDER"
PACKAGE."type"
PACKAGE."code"

TablesList:

"DBNAME"."USER" USER
"DBNAME2"."PACKAGE" PACKAGE

Upvotes: 1

Views: 4588

Answers (1)

Tim.Tang
Tim.Tang

Reputation: 3188

Use this Regex will get the column and table name:

  (?is)SELECT(.*?)(?<!\w*")FROM(?!\w*?")(.*?)(?=WHERE|ORDER|$)
  • Group[1] :　column
  • Group[2] : table name

Code Samples:

string sql=@"SELECT
    USER.""ID"", USER.""NAME"", USER.""BIRTH"",USER.""GENDER"",
    PACKAGE.""type""
    PACKAGE.""code""
FROM
    ""DBNAME"".""USER"" USER,
    ""DBNAME2"".""PACKAGE"" PACKAGE
WHERE
    USER.""PACKAGE_ID"" = PACKAGE.""ID""
ORDER BY
    USER.""NAME"";";

    var reg=new Regex(@"(?is)SELECT(.*?)(?<!\w*"")FROM(?!\w*?"")(.*?)(?=WHERE|ORDER|$)");
    var colunms=reg.Match(sql).Groups[1].Value.Split(new char[]{','},StringSplitOptions.RemoveEmptyEntries);
    var tables=reg.Match(sql).Groups[2].Value.Split(new char[]{','},StringSplitOptions.RemoveEmptyEntries);

Upvotes: 5

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