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ebnf select #17275

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May 9, 2024
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ebnf select #17275

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ebnf select
dveeden Apr 19, 2024
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dveeden Apr 19, 2024
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Update sql-statements/sql-statement-select.md
dveeden Apr 19, 2024
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Update sql-statements/sql-statement-select.md
dveeden Apr 19, 2024
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dveeden Apr 30, 2024
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82 changes: 23 additions & 59 deletions sql-statements/sql-statement-select.md
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Expand Up @@ -10,84 +10,48 @@ The `SELECT` statement is used to read data from TiDB.

## Synopsis

**SelectStmt:**

![SelectStmt](/media/sqlgram/SelectStmt.png)

**FromDual:**

![FromDual](/media/sqlgram/FromDual.png)

**SelectStmtOpts:**
```ebnf+diagram
SelectStmt ::=
( SelectStmtBasic | SelectStmtFromDualTable | SelectStmtFromTable )
OrderBy? SelectStmtLimit? SelectLockOpt? SelectStmtIntoOption

![SelectStmtOpts](/media/sqlgram/SelectStmtOpts.png)
SelectStmtBasic ::=
"SELECT" SelectStmtOpts Field ("," Field)* ( "HAVING" Expression)?

**SelectStmtFieldList:**
SelectStmtFromDualTable ::=
"SELECT" SelectStmtOpts Field ("," Field)* "FROM" "DUAL" WhereClause?

![SelectStmtFieldList](/media/sqlgram/SelectStmtFieldList.png)
SelectStmtFromTable ::=
"SELECT" SelectStmtOpts Field ("," Field)* "FROM" TableRefsClause
WhereClause? GroupByClause? ( "HAVING" Expression)? WindowClause?

**TableRefsClause:**
SelectStmtOpts ::=
TableOptimizerHints DefaultFalseDistictOpt PriorityOpt SelectStmtSQLSmallResult
SelectStmtSQLBigResult SelectStmtSQLBufferResult SelectStmtSQLCache SelectStmtCalcFoundRows
SelectStmtStraightJoin

```ebnf+diagram
TableRefsClause ::=
TableRef AsOfClause? ( ',' TableRef AsOfClause? )*

AsOfClause ::=
'AS' 'OF' 'TIMESTAMP' Expression
```

**WhereClauseOptional:**

![WhereClauseOptional](/media/sqlgram/WhereClauseOptional.png)

**SelectStmtGroup:**

![SelectStmtGroup](/media/sqlgram/SelectStmtGroup.png)

**HavingClause:**

![HavingClause](/media/sqlgram/HavingClause.png)

**OrderByOptional:**

![OrderByOptional](/media/sqlgram/OrderByOptional.png)
SelectStmtLimit ::=
("LIMIT" LimitOption ( ("," | "OFFSET") LimitOption )?
| "FETCH" ("FIRST" | "NEXT") LimitOption? ("ROW" | "ROWS") "ONLY" )

**SelectStmtLimit:**

![SelectStmtLimit](/media/sqlgram/SelectStmtLimit.png)

**FirstOrNext:**

![FirstOrNext](/media/sqlgram/FirstOrNext.png)

**FetchFirstOpt:**

![FetchFirstOpt](/media/sqlgram/FetchFirstOpt.png)

**RowOrRows:**

![RowOrRows](/media/sqlgram/RowOrRows.png)

**SelectLockOpt:**

```ebnf+diagram
SelectLockOpt ::=
( ( 'FOR' 'UPDATE' ( 'OF' TableList )? 'NOWAIT'? )
| ( 'LOCK' 'IN' 'SHARE' 'MODE' ) )?
( 'FOR' 'UPDATE' ( 'OF' TableList )? 'NOWAIT'?
| 'LOCK' 'IN' 'SHARE' 'MODE' )

TableList ::=
TableName ( ',' TableName )*
```

**WindowClauseOptional**
WindowClause ::=
"WINDOW" WindowDefinition ("," WindowDefinition)*

![WindowClauseOptional](/media/sqlgram/WindowClauseOptional.png)

**TableSampleOpt**

```ebnf+diagram
TableSampleOpt ::=
'TABLESAMPLE' 'REGIONS()'
'TABLESAMPLE' 'REGIONS' '(' ')'
```

## Description of the syntax elements
Expand Down
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