@uwdata/mosaic-sql/dist/src/ast/from.js

SQL query construction and analysis.

import { FROM_CLAUSE } from '../constants.js';
import { quoteIdentifier } from '../util/string.js';
import { SQLNode } from './node.js';
import { isQuery } from './query.js';
import { isTableRef } from './table-ref.js';
export class FromClauseNode extends SQLNode {
    /** The from expression. */
    expr;
    /** The output name. */
    alias;
    /** The table sample. */
    sample;
    /**
     * Instantiate a from node.
     * @param expr The from expression.
     * @param alias The output name.
     * @param sample The table sample.
     */
    constructor(expr, alias, sample) {
        super(FROM_CLAUSE);
        this.expr = expr;
        this.alias = alias;
        this.sample = sample;
    }
    /**
     * Generate a SQL query string for this node.
     */
    toString() {
        const { expr, alias, sample } = this;
        const ref = isQuery(expr) ? `(${expr})` : `${expr}`;
        const from = alias && !(isTableRef(expr) && expr.table.join('.') === alias)
            ? `${ref} AS ${quoteIdentifier(alias)}`
            : `${ref}`;
        return `${from}${sample ? ` TABLESAMPLE ${sample}` : ''}`;
    }
}
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